umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1 - 34 av 34
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Arnqvist, Anna
    et al.
    Olsén, A
    Normark, S
    Sigma S-dependent growth-phase induction of the csgBA promoter in Escherichia coli can be achieved in vivo by sigma 70 in the absence of the nucleoid-associated protein H-NS.1994Ingår i: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 13, nr 6, s. 1021-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stationary-phase-specific sigma factor sigma S (RpoS/KatF) is required for Escherichia coli to induce expression of fibronectin-binding curli organelles upon reaching stationary phase. We show that the csgA gene which encodes the curlin subunit protein belongs to a dicistronic operon, csgBA. The transcriptional start site of csgBA was determined and an AT-rich up-stream activating sequence (UAS) required for transcriptional activation was identified. The pcsgBA promoter is not specific for sigma S since the same promoter sequence can be used by E sigma 70 in vivo in a strain lacking nucleoid-associated protein H-NS and sigma S. Transcription remained growth-phase induced and dependent upon the UAS in such a double mutant. Furthermore, we demonstrate that an additional operon, hdeAB, which is also dependent upon sigma S for transcription, can be transcribed by E sigma 70 in vivo in the absence of H-NS by utilizing the phdeAB promoter. Two other genes known to be under the control of sigma S for expression, bolA and katE, remained transcriptionally silent in the absence of H-NS. It is suggested that a subset of E. coli promoters can be recognized by both E sigma S and E sigma 70 in vivo but H-NS interacting with these sequences prevents formation of successful transcription-initiation complexes with E sigma 70.

  • 2. Arnqvist, Anna
    et al.
    Olsén, A
    Pfeifer, J
    Russell, D G
    Normark, S
    The Crl protein activates cryptic genes for curli formation and fibronectin binding in Escherichia coli HB101.1992Ingår i: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 6, nr 17, s. 2443-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Curli are thin, coiled, temperature-regulated fibres on fibronectin-binding Escherichia coli. The subunit protein of curli was highly homologous at its amino terminus to SEF-17, the subunit protein of thin, aggregative fimbriae of Salmonella enteritidis 27655 strain 3b, suggesting that these fibres form a novel class of surface organelles on enterobacteria. E. coli HB101 is non-curliated and unable to bind soluble, iodinated fibronectin. The phenotypically cryptic curlin subunit gene, csgA, in HB101 is transcriptionally activated by expressing the cytoplasmic Crl on a multicopy plasmid. Transcriptional activation of csgA by Crl was observed after growth at 26 degrees C but not at 37 degrees C, even though crl transcription was not thermoregulated. A deletion of the 39 carboxy-terminal residues abolished Crl activity, whereas a deletion of 10 residues at the C-terminus did not, implying that a region between residue 93 and 122 in the 132-amino-acid-residue large Crl protein is required for activating curli expression in E. coli HB101. crl is a normal housekeeping gene in E. coli and it is suggested that its gene product may either be a DNA-binding protein affecting chromatin structure as has been suggested for histone-like protein H1 or interact with specific regulatory protein(s) controlling transcription of genes required for curli formation and fibronectin binding.

  • 3. Aspholm, Marina
    et al.
    Kalia, Awdhesh
    Ruhl, Stefan
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Lindén, Sara
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gerhard, Markus
    Semino-Mora, Cristina
    Dubois, Andre
    Unemo, Magnus
    Danielsson, Dan
    Teneberg, Susann
    Lee, Woo-Kon
    Berg, Douglas E
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Helicobacter pylori adhesion to carbohydrates.2006Ingår i: Methods in enzymology, ISSN 0076-6879, Vol. 417, s. 293-339Artikel i tidskrift (Refereegranskat)
  • 4. Aspholm, Marina
    et al.
    Olfat, Farzad O
    Nordén, Jenny
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sondén, Berit
    Lundberg, Carina
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Altraja, Siiri
    Odenbreit, Stefan
    Haas, Rainer
    Wadström, Torkel
    Engstrand, Lars
    Semino-Mora, Cristina
    Liu, Hui
    Dubois, André
    Teneberg, Susann
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    SabA is the H. pylori hemagglutinin and is polymorphic in binding to sialylated glycans.2006Ingår i: PLoS Pathog, ISSN 1553-7374, Vol. 2, nr 10, s. e110-Artikel i tidskrift (Refereegranskat)
  • 5.
    Aspholm-Hurtig, Marina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Dailide, Giedrius
    Lahmann, Martina
    Kalia, Awdhesh
    Ilver, Dag
    Roche, Niamh
    Vikström, Susanne
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Lindén, Sara
    Bäckström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Lundberg, Carina
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Mahdavi, Jafar
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Nilsson, Ulf J
    Velapatiño, Billie
    Gilman, Robert H
    Gerhard, Markus
    Alarcon, Teresa
    López-Brea, Manuel
    Nakazawa, Teruko
    Fox, James G
    Correa, Pelayo
    Dominguez-Bello, Maria Gloria
    Perez-Perez, Guillermo I
    Blaser, Martin J
    Normark, Staffan
    Carlstedt, Ingemar
    Oscarson, Stefan
    Teneberg, Susann
    Berg, Douglas E
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin2004Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 305, nr 5683, s. 519-522Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.

  • 6.
    Basmarke-Wehelie, Rahma
    et al.
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Swede.
    Sjolinder, Hong
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Swede.
    Jurkowski, Wiktor
    Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
    Elofsson, Arne
    Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Engstrand, Lars
    Swedish Institute for Infectious Disease Control, Karolinska Institutet, Solna, Sweden .
    Hagner, Matthias
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
    Wallin, Elin
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
    Guan, Na
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
    Kuranasekera, Hasanthi
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
    Aro, Helena
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
    Jonsson, Ann-Beth
    Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden.
    The Complement Regulator CD46 Is Bactericidal to Helicobacter pylori and Blocks Urease Activity2011Ingår i: Gastroenterology, ISSN 0016-5085, E-ISSN 1528-0012, Vol. 141, nr 3, s. 918-928Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background & Aims: CD46 is a C3b/C4b binding complement regulator and a receptor  for several human pathogens. We examined the interaction between CD46 and Helicobacter pylori (a bacterium that colonizes the human gastric mucosa and causes gastritis), peptic ulcers, and cancer.

    Methods: Using gastric epithelial cells, we analyzed a set of H pylori strains and mutants for their ability to interact with CD46 and/or influence CD46 expression. Bacterial interaction with full-length CD46 and small CD46 peptides was evaluated by flow cytometry, fluorescence microscopy, enzyme-linked immunosorbent assay, and bacterial survival analyses.

    Results: H pylori infection caused shedding of CD46 into the extracellular environment. A soluble form of CD46 bound to H pylori and inhibited growth, in a dose- and time-dependent manner, by interacting with urease and alkyl hydroperoxide reductase, which are essential bacterial pathogenicity-associated factors. Binding of CD46 or CD46-derived synthetic peptides blocked theurease activity and ability of bacteria to survive in acidic environments. Oral administration of one CD46 peptide eradicated H pylori from infected mice.

    Conclusions: CD46 is an antimicrobial agent that can eradicate H pylori. CD46 peptides might be developed to treat H pylori infection.

  • 7.
    Bugaytsova, Jeanna A.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Björnham, Oscar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Swedish Defence Research Agency, 906 21 Umeå, Sweden.
    Chernov, Yevgen A.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Henriksson, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Mendez, Melissa
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Mahdavi, Jafar
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. School of Life Sciences, CBS, University of Nottingham, NG7 2RD Nottingham, UK.
    Shevtsova, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Ilver, Dag
    Moonens, Kristof
    Quintana-Hayashi, Macarena P.
    Moskalenko, Roman
    Aisenbrey, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bylund, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Schmidt, Alexej
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Åberg, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Koeniger, Verena
    Vikström, Susanne
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Rakhimova, Lena
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Hofer, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Ögren, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Liu, Hui
    Goldman, Matthew D.
    Whitmire, Jeannette M.
    Åden, Jörgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Younson, Justine
    Kelly, Charles G.
    Gilman, Robert H.
    Chowdhury, Abhijit
    Mukhopadhyay, Asish K.
    Nair, G. Balakrish
    Papadakos, Konstantinos S.
    Martinez-Gonzalez, Beatriz
    Sgouras, Dionyssios N.
    Engstrand, Lars
    Unemo, Magnus
    Danielsson, Dan
    Suerbaum, Sebastian
    Oscarson, Stefan
    Morozova-Roche, Ludmilla A.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Olofsson, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Holgersson, Jan
    Esberg, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Strömberg, Nicklas
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Landström, Maréne
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Eldridge, Angela M.
    Chromy, Brett A.
    Hansen, Lori M.
    Solnick, Jay V.
    Linden, Sara K.
    Haas, Rainer
    Dubois, Andre
    Merrell, D. Scott
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Remaut, Han
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Berg, Douglas E.
    Boren, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence2017Ingår i: Cell Host and Microbe, ISSN 1931-3128, E-ISSN 1934-6069, Vol. 21, nr 3, s. 376-389Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease.

  • 8.
    Bugaytsova, Jeanna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Björnhamn, Oscar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Henriksson, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Johansson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Mendez, Melissa
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Aisenbrey, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shevtsova, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Bylund, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Mahdavi, Jafar
    Ögren, Johan
    Ilver, Dag
    Gilman, Robert H
    Chowdhury, Abhijit
    The Swedish Institute for Control, Solna, Swede.
    Mukhopadhyay, Asish K
    Engstrand, Lars
    Oscarson, Stefan
    Kelly, Charles G
    Younson, Justine S
    Odenbreit, Stefan
    Solnick, Jay
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Haas, Rainer
    Dubois, Andre
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Berg, Douglas E
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    pH regulated H. pylori adherence: implications for persistent infection and diseaseManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Helicobacter pylori’s BabA adhesin binds strongly to gastric mucosal ABH/Leb glycans on the stomach epithelium and overlying mucus, materials continuously shed into the acidic gastric lumen. Here we report that this binding is acid labile, acid inactivation is fully reversible; and acid lability profiles vary with BabA sequence and correlate with disease patterns. Isogenic H. pylori strains from the gastric antrum and more acidic corpus were identified that differed in acid lability of receptor binding and in sequence near BabA’s carbohydrate binding domain. We propose that reversible acid inactivation of receptor binding helps H. pylori avoid clearance by mucosal shedding, and that strain differences in acid lability affect tissue tropism and the spectrum of associated gastric diseases.

  • 9.
    Bugaytsova, Jeanna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Chernov, Yevgen A
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Mendez, Melissa
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Henriksson, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Mahdavi, Jafar
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. School of Life Sciences, CBS, University of Nottingham, Nottingham, UK..
    Quintana-Hayashi, Macarena
    Department of Biochemistry and Cell biology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden..
    Shevtsova, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sjöström, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Moskalenko, Roman
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Department of Pathology, Medical Institute, State University, Sumy, Ukraine.
    Aisenbrey, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Université de Strasbourg, Institut de Chimie, Strasbourg, France.
    Moonens, Kristof
    Structural and Molecular Microbiology, VIB Department of Structural Biology, Belgium.
    Björnham, Oscar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. FOI Totalförsvarets Forskningsinstitut, Umeå, Sweden..
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Bylund, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Königer, Verena
    Max von Pettenkofer Institute of Hygiene and Medical Microbiology, LMU, Munich, Germany.
    Vikström, Susanne
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Schmidt, Alexej
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Rakhimova, Lena
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Hofer, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Ögren, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Ilver, Dag
    Department of Biochemistry and Cell biology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Liu, Hui
    Department of Medicine, USUHS, Bethesda, MD, USA.
    Goldman, Matthew
    Department of Pediatrics, USUHS, Bethesda, MD, USA.
    Whitmire, Jeannette M
    Department of Microbiology and Immunology, USUHS, Bethesda, MD USA.
    Kelly, Charles G
    King's College London, Dental Institute, London, UK.
    Gilman, Robert H
    Department of International Health, John Hopkins School of Public Health, Baltimore, MD, USA.
    Chowdhury, Abhijit
    Centre for Liver Research, School of Digestive and Liver Diseases, Institute of Post Graduate Medical Education & Research, Kolkata, India.
    Mukhopadhyay, Asish K
    Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India.
    Nair, Balakrish G
    Translational Health Science and Technology Institute, Haryana, India.
    Papadakos, Konstantinos S
    Hellenic Pasteur Institute, Athens, Greece.
    Martinez-Gonzalez, Beatriz
    Hellenic Pasteur Institute, Athens, Greece.
    Sgouras, Dionyssios N
    Hellenic Pasteur Institute, Athens, Greece.
    Engstrand, Lars
    Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
    Unemo, Magnus
    Department of Laboratory Medicine, Microbiology, Örebro University Hospital, Örebro, Sweden.
    Danielsson, Dan
    Department of Laboratory Medicine, Microbiology, Örebro University Hospital, Örebro, Sweden.
    Sebastian, Suerbaum
    Institute for Medical Microbiology and Hospital Epidemiology Hannover Medical School, Hannover, Germany.
    Oscarson, Stefan
    Centre for Synthesis and Chemical Biology, School of Chemistry, University College Dublin, Dublin, Ireland.
    Morozova-Roche, Ludmilla
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Holgersson, Jan
    Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Strömberg, Nicklas
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Esberg, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Eldridge, Angela
    Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento, CA, USA.
    Chromy, Brett A
    Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento, CA, USA.
    Hansen, Lori
    Departments of Medical Microbiology and Immunology, Center for Comparative Medicine, University of California Davis, Davis, CA, USA.
    Solnick, Jay
    Departments of Medical Microbiology and Immunology, Center for Comparative Medicine, University of California Davis, Davis, CA, USA.
    Haas, Rainer
    Max von Pettenkofer Institute of Hygiene and Medical Microbiology, LMU Munich, Munich, Germany.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindén, Sara K
    Department of Biochemistry and Cell biology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Dubois, Andre
    Department of Medicine, USUHS, Bethesda, MD, USA.
    Merrell, D. Scott
    Department of Microbiology and Immunology, USUHS, Bethesda, MD, USA.
    Remaut, Han
    Structural and Molecular Microbiology, VIB Department of Structural Biology, VIB, Brussels, Belgium.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Berg, Douglas E
    Department of Medicine, University of California San Diego, La Jolla, CA, USA.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Acid Responsive Helicobacter pylori Adherence: Implications for Chronic Infection and DiseaseManuskript (preprint) (Övrigt vetenskapligt)
  • 10.
    Bäckström, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Lundberg, Carina
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Kersulyte, Dangeruta
    Berg, Douglas E
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Metastability of Helicobacter pylori bab adhesin genes and dynamics in Lewis b antigen binding2004Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 101, nr 48, s. 16923-16928Artikel i tidskrift (Refereegranskat)
  • 11. Fujimoto, Saori
    et al.
    Olaniyi Ojo, Olabisi
    Arnqvist, Anna
    Umeå universitet, Medicinsk fakultet, Medicinsk kemi och biofysik.
    Wu, Jeng Yih
    Odenbreit, Stefan
    Haas, Rainer
    Graham, David Y
    Yamaoka, Yoshio
    Helicobacter pylori BabA expression, gastric mucosal injury, and clinical outcome.2007Ingår i: Clin Gastroenterol Hepatol, ISSN 1542-7714, Vol. 5, nr 1, s. 49-58Artikel i tidskrift (Refereegranskat)
  • 12. Hammar, M
    et al.
    Arnqvist, Anna
    Bian, Z
    Olsén, A
    Normark, S
    Expression of two csg operons is required for production of fibronectin- and congo red-binding curli polymers in Escherichia coli K-12.1995Ingår i: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 18, nr 4, s. 661-70Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two divergently transcribed operons in Escherichia coli required for the expression of fibronectin- and Congo red-binding curli polymers were identified and characterized by transposon mutagenesis, sequencing and transcriptional analyses, as well as for their ability to produce the curli subunit protein. The csgBA operon encodes CsgA, the major subunit protein of the fibre, and CsgB, a protein with sequence homology to CsgA. A non-polar csgB mutant is unaffected in its production of CsgA, but the subunit protein is not assembled into insoluble fibre polymers. A third open reading frame, orfC, positioned downstream of csgA may affect some functional property of curli since an insertion in this putative gene abolishes the autoagglutinating ability typical of curliated cells without affecting the production of the fibre. The promoter for the oppositely transcribed csgDEFG operon was identified by primer extension and shown, like the csgBA promoter, to be dependent upon the alternate stationary phase-specific sigma factor sigma s in wild-type cells, but not in mutants lacking the nucleoid associated protein H-NS. Insertions in csgD abolish completely trancription from the csgBA promoter. Therefore, any regulatory effect on the csgBA promoter might be secondary to events controlling the csgDEFG promoter and/or activation of CsgD. Insertions in csgE, csgF and csgG abolish curli formation but allow CsgA expression suggesting that one or more of these gene products are involved in secretion/assembly of the CsgA subunit protein. No amino acid sequence homologies were found between the CsgE, CsgF and CsgG proteins and secretion/assembly proteins for other known bacterial fibres, suggesting that the formation of curli follows a novel pathway.

  • 13. Ilver, D
    et al.
    Arnqvist, Anna
    Ogren, J
    Frick, I M
    Kersulyte, D
    Incecik, E T
    Berg, D E
    Covacci, A
    Engstrand, L
    Borén, Thomas
    Helicobacter pylori adhesin binding fucosylated histo-blood group antigens revealed by retagging.1998Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 279, nr 5349, s. 373-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The bacterium Helicobacter pylori is the causative agent for peptic ulcer disease. Bacterial adherence to the human gastric epithelial lining is mediated by the fucosylated Lewis b (Leb) histo-blood group antigen. The Leb-binding adhesin, BabA, was purified by receptor activity-directed affinity tagging. The bacterial Leb-binding phenotype was associated with the presence of the cag pathogenicity island among clinical isolates of H. pylori. A vaccine strategy based on the BabA adhesin might serve as a means to target the virulent type I strains of H. pylori.

  • 14. Lekmeechai, Sujinna
    et al.
    Su, Yu-Ching
    Brant, Marta
    Alvarado-Kristensson, Maria
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Obi, Ikenna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Riesbeck, Kristian
    Helicobacter pylori Outer Membrane Vesicles Protect the Pathogen From Reactive Oxygen Species of the Respiratory Burst2018Ingår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, artikel-id 1837Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Outer membrane vesicles (OMVs) play an important role in the persistence of Helicobacter pylori infection. Helicobacter OMVs carry a plethora of virulence factors, including catalase (KatA), an antioxidant enzyme that counteracts the host respiratory burst. We found KatA to be enriched and surface-associated in OMVs compared to bacterial cells. This conferred OMV-dependent KatA activity resulting in neutralization of H2O2 and NaClO, and rescue of surrounding bacteria from oxidative damage. The antioxidant activity of OMVs was abolished by deletion of KatA. In conclusion, enrichment of antioxidative KatA in OMVs is highly important for efficient immune evasion.

  • 15. Lindén, S. K.
    et al.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Teneberg, S.
    Moran, A. P.
    Helicobacter pylori Adhesion to the Gastric Surface2010Ingår i: Helicobacter pylori in the 21st Century / [ed] Sutton, P. Mitchell, H, WALLINGFORD: CABI Publishing, 2010, nr 17, s. 248-268Kapitel i bok, del av antologi (Refereegranskat)
  • 16.
    Mahdavi, Jafar
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Sondén, B
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Hurtig, Marina
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Olfat, Farzad O
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Forsberg, Lina
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Roche, Niamh
    Ångström, Jonas
    Larsson, Thomas
    Teneberg, Susann
    Karlsson, Karl-Anders
    Altraja, Siiri
    Wadström, Torkel
    Kersulyte, Dangeruta
    Berg, Douglas E
    Dubois, Andre
    Petersson, Christoffer
    Magnusson, Karl-Eric
    Norberg, Thomas
    Lindh, Frank
    Lundskog, Bertil B
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Hammarström, Lennart
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation2002Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 297, nr 5581, s. 573-578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Helicobacter pylori adherence in the human gastric mucosa involves specific bacterial adhesins and cognate host receptors. Here, we identify sialyl-dimeric-Lewis x glycosphingolipid as a receptor for H. pylori and show that H. pylori infection induced formation of sialyl-Lewis x antigens in gastric epithelium in humans and in a Rhesus monkey. The corresponding sialic acid-binding adhesin (SabA) was isolated with the "retagging" method, and the underlying sabA gene (JHP662/HP0725) was identified. The ability of many H. pylori strains to adhere to sialylated glycoconjugates expressed during chronic inflammation might thus contribute to virulence and the extraordinary chronicity of H. pylori infection.

  • 17. Moonens, Kristof
    et al.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Subedi, Suresh
    Bugaytsova, Jeanna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Romao, Ema
    Mendez, Melissa
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Nordén, Jenny
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Fallah, Mahsa
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Rakhimova, Lena
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Shevtsova, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Lahmann, Martina
    Castaldo, Gaetano
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Coppens, Fanny
    Lo, Alvin W.
    Ny, Tor
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Solnick, Jay V.
    Vandenbussche, Guy
    Oscarson, Stefan
    Hammarström, Lennart
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Berg, Douglas E.
    Muyldermans, Serge
    Borén, Thomas
    Remaut, Han
    Structural Insights into Polymorphic ABO Glycan Binding by Helicobacter pylori2016Ingår i: Cell Host and Microbe, ISSN 1931-3128, E-ISSN 1934-6069, Vol. 19, nr 1, s. 55-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Helicobacter pylori adhesin BabA binds mucosal ABO/Le b blood group (bg) carbohydrates. BabA facilitates bacterial attachment to gastric surfaces, increasing strain virulence and forming a recognized risk factor for peptic ulcers and gastric cancer. High sequence variation causes BabA functional diversity, but the underlying structural-molecular determinants are unknown. We generated X-ray structures of representative BabA isoforms that reveal a polymorphic, three-pronged Le(b) binding site. Two diversity loops, DL1 and DL2, provide adaptive control to binding affinity, notably ABO versus O bg preference. H. pylori strains can switch bg preference with single DL1 amino acid substitutions, and can coexpress functionally divergent BabA isoforms. The anchor point for receptor binding is the embrace of an ABO fucose residue by a disulfide-clasped loop, which is inactivated by reduction. Treatment with the redox-active pharmaceutic N-acetylcysteine lowers gastric mucosal neutrophil infiltration in H. pylori-infected Le(b)-expressing mice, providing perspectives on possible H. pylori eradication therapies.

  • 18. Ohno, Tomoyuki
    et al.
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Rugge, Massimo
    Ota, Hiroyoshi
    Graham, David Y
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Yamaoka, Yoshio
    Effects of blood group antigen-binding adhesin expression during Helicobacter pylori infection of Mongolian gerbils2011Ingår i: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 203, nr 5, s. 726-735Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Helicobacter pylori outer membrane proteins, such as the blood group antigen-binding adhesin (BabA), are associated with severe pathological outcomes. However, the in vivo role of BabA during long-term infection is not clear. In this study, Mongolian gerbils were infected with H. pylori and necropsied continuously during 18 months. Bacterial clones were recovered and analyzed for BabA expression, Leb-binding activity, and adhesion to gastric mucosa. BabA expression was completely absent by 6 months post-infection. Loss of BabA expression was attributable to nucleotide changes within the babA gene that resulted in a truncated BabA. In response to the infection, changes in the epithelial glycosylation pattern were observed that were similar to responses observed in humans and monkeys. Furthermore, infections with BabA-expressing and BabA-nonexpressing H. pylori showed no differences in colonization, but infection with the BabA-expressing strain exhibited histological changes and increased inflammatory cell infiltration. This suggests that BabA expression contributes to severe mucosal injury.

  • 19.
    Ohno, Tomoyuki
    et al.
    Department of Medicine-Gastroenterology, Michael E. DeBakey Vetrans Medical Center and Baylor College of Medicine, Houston, Texas, USA.
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Wu, MJ
    Rugge, Massimo
    Department of Diagnostic Science and Special Therapies (Pathology Unit), University of Padova, Padova, Italy.
    Ota, Hiroyoshi
    Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University School of Medicine, Matsumoto, Japan.
    Graham, David Y
    Department of Medicine-Gastroenterology, Michael E. DeBakey Vetrans Medical Center and Baylor College of Medicine, Houston, Texas, USA.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Yamaoka, Yoshio
    Department of Medicine-Gastroenterology, Michael E. DeBakey Vetrans Medical Center and Baylor College of Medicine, Houston, Texas, USA and Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Yufu, Japan.
    Effects of BabA expression during H. pylori infection of Mongolian gerbilsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Objective: Helicobacter pylori outer membrane proteins, such as the BabA adhesin are associated with severe pathological outcome.  However, the in vivo role of the BabA adhesin during long-term infection is not clear.  Design and Setting: Mongolian gerbils were inoculated with the H. pylori TN2GF4 and were necropsied at 1, 3, 6, and 18 months.  Main outcome measures: Bacterial clones recovered from the infected gerbils were evaluated by immunoblot for BabA expression, radioimmunoassay for Leb-binding, and bacterial binding to gastric tissue.  H1 antigen expression and the increase in sialylation levels were monitored by immunohistochemistry.  Results: BabA expression increased, then progressively decreased, and was completely absent by 6 months post-infection.  Loss of BabA expression was caused by nucleotide changes/deletions within the babA gene that resulted in a truncated BabA.  Infection with a BabA-expressing H. pylori caused severe mucosal injury, whereas infection with a BabA non-expressing strain caused only mild inflammation.  In response to the infection, changes in the epithelial glycosylation pattern were observed, similar to responses observed in humans and monkeys.  Conclusion: Down-regulation of BabA is probably a result of adaptation to the host response during long-term H. pylori infection.  BabA expression is most likely not essential for colonisation, but for the obtained gerbil host response, which confirms the role of BabA adhesin as a virulence factor and its impact in the induction of a severe inflammatory response.  The changes in glycosylation of gastric mucosa demonstrate the relevance of the Mongolian gerbil as a model for H. pylori infection and host responses.

  • 20.
    Olofsson, Annelie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Nygård Skalman, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Obi, Ikenna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Lundmark, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Uptake of Helicobacter pylori vesicles is facilitated by clathrin-dependent and clathrin-independent endocytic pathways2014Ingår i: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 5, nr 3, s. e00979-14-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    UNLABELLED: Bacteria shed a diverse set of outer membrane vesicles that function as transport vehicles to deliver effector molecules and virulence factors to host cells. Helicobacter pylori is a gastric pathogen that infects half of the world's population, and in some individuals the infection progresses into peptic ulcer disease or gastric cancer. Here we report that intact vesicles from H. pylori are internalized by clathrin-dependent endocytosis and further dynamin-dependent processes, as well as in a cholesterol-sensitive manner. We analyzed the uptake of H. pylori vesicles by gastric epithelial cells using a method that we refer to as quantification of internalized substances (qIS). The qIS assay is based on a near-infrared dye with a cleavable linker that enables the specific quantification of internalized substances after exposure to reducing conditions. Both chemical inhibition and RNA interference in combination with the qIS assay showed that H. pylori vesicles enter gastric epithelial cells via both clathrin-mediated endocytosis and additional endocytic processes that are dependent on dynamin. Confocal microscopy revealed that H. pylori vesicles colocalized with clathrin and dynamin II and with markers of subsequent endosomal and lysosomal trafficking. Interestingly, however, knockdown of components required for caveolae had no significant effect on internalization and knockdown of components required for clathrin-independent carrier (CLIC) endocytosis increased internalization of H. pylori vesicles. Furthermore, uptake of vesicles by both clathrin-dependent and -independent pathways was sensitive to depletion, but not sequestering, of cholesterol in the host cell membrane suggesting that membrane fluidity influences the efficiency of H. pylori vesicle uptake.

    IMPORTANCE: Bacterial vesicles act as long-distance tools to deliver toxins and effector molecules to host cells. Vesicles can cause a variety of host cell responses via cell surface-induced cell signaling or internalization. Vesicles of diverse bacterial species enter host cells via different endocytic pathways or via membrane fusion. With the combination of a fluorescence-based quantification assay that quantifies internalized vesicles in a large number of cells and either chemical inhibition or RNA interference, we show that clathrin-mediated endocytosis is the major pathway for uptake of Helicobacter pylori vesicles and that lipid microdomains of the host cell membrane affect uptake of vesicles via clathrin-independent pathways. Our results provide important insights about membrane fluidity and its important role in the complex process that directs the H. pylori vesicle to a specific endocytic pathway. Understanding the mechanisms that operate in vesicle-host interactions is important to fully recognize the impact of vesicles in pathogenesis.

  • 21.
    Olofsson, Annelie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Petzold, Katja
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Carlsson, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Haas, Rainer
    Max-von-Pettenkofer-Institute of Hygiene and Medical Microbiology, Dept of Bacteriology, Munich, Germany.
    Backert, Steffen
    School of Biomolecular and Biomedical Sciences, University College Dublin, Ireland.
    Nyunt Wai, Sun
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Characterization of Helicobacter pylori vesicles and their cognate properties for intimate host interactionsManuskript (preprint) (Övrigt vetenskapligt)
  • 22.
    Olofsson, Annelie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Petzold, Katja
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Tegtmeyer, Nicole
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Carlsson, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Haas, Rainer
    Backert, Steffen
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Biochemical and functional characterization of Helicobacter pylori vesicles2010Ingår i: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 77, nr 6, s. 1539-1555Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Helicobacter pylori can cause peptic ulcer disease and/or gastric cancer. Adhesion of bacteria to the stomach mucosa is an important contributor to the vigor of infection and resulting virulence. H. pylori adheres primarily via binding of BabA adhesins to ABO/Lewis b (Leb) blood group antigens and the binding of SabA adhesins to sialyl-Lewis x/a (sLex/a) antigens. Similar to most Gram-negative bacteria, H. pylori continuously buds off vesicles and vesicles derived from pathogenic bacteria often include virulence-associated factors. Here we biochemically characterized highly purified H. pylori vesicles. Major protein and phospholipid components associated with the vesicles were identified with mass spectroscopy and NMR. A subset of virulence factors present was confirmed by immunoblots. Additional functional and biochemical analysis focused on the vesicle BabA and SabA adhesins and their respective interactions to human gastric epithelium. Vesicles exhibit heterogeneity in their protein composition, which were specifically studied in respect to the BabA adhesin. We also demonstrate that the oncoprotein, CagA, is associated with the surface of H. pylori vesicles. Thus, we have explored mechanisms for intimate H. pylori vesicle-host interactions and found that the vesicles carry effector-promoting properties that are important to disease development.

  • 23. Olsén, A
    et al.
    Arnqvist, Anna
    Hammar, M
    Normark, S
    Environmental regulation of curli production in Escherichia coli.1993Ingår i: Infectious agents and disease, ISSN 1056-2044, Vol. 2, nr 4, s. 272-4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Curli are novel surface organelles on E. coli that mediate binding to soluble matrix proteins. The expression of curli is affected by environmental factors, such as temperature, osmolarity, and growth conditions. Curli formation is regulated at the level of transcription, in that the csgA gene can be transcriptionally activated by the cytosolic Crl protein or transcriptionally relieved by a mutation in hns. The expression of curli is also dependent on functional RpoS. E. coli--expressing curli bind to human skin tissue, provided they are precoated with soluble fibronectin, suggesting that curli may act as a colonization factor in host-microbe interactions. Fibronectin is a multifunctional extracellular matrix and plasma protein involved in cell adhesion and cell spreading. It also interacts with a variety of microorganisms, and thus the role of fibronectin in mediating binding of curliated E. coli is of great interest. An investigation of the epitopes of both the fibronectin molecule and the curlin subunit protein involved in the binding of E. coli to tissue will give us more insight into the initial colonization of host surfaces by bacteria.

  • 24. Olsén, A
    et al.
    Arnqvist, Anna
    Hammar, M
    Sukupolvi, S
    Normark, S
    The RpoS sigma factor relieves H-NS-mediated transcriptional repression of csgA, the subunit gene of fibronectin-binding curli in Escherichia coli.1993Ingår i: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 7, nr 4, s. 523-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Curli encoded by the curlin subunit gene, csgA, are fibronectin- and laminin-binding fibres expressed by many natural Escherichia coli and E. coli K-12 strains in response to low temperature, low osmolarity and stationary-phase growth conditions. Curli expression is dependent on RpoS, a sigma factor that controls many stationary phase-inducible genes. Many commonly used K-12 strains carry an amber mutation in rpoS. Strains able to form curli carry an amber suppressor whereas curli-negative E. coli K-12 strains, in general, are sup0. Introduction of SupD, SupE, or supF suppressors into sup0 strains resulted in expression of temperature-regulated curli. In curli-deficient, RpoS- E. coli K-12 strains, csgA is transcriptionally activated by mutations in hns, which encodes the histone-like protein H-NS. Curli expression, fibronectin binding, and csgA transcription remain temperature- and osmoregulated in such double mutants. Our data suggest that RpoS+ strains, and hence curli-proficient strains of E. coli K-12, are relieved for the transcriptional repression mediated by the H-NS protein upon accumulating RpoS as cells reach stationary phase.

  • 25.
    Olsén, Arne
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Jonsson, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Normark, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Fibronectin binding mediated by a novel class of surface organelles on Escherichia coli1989Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 338, nr 6217, s. 652-5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gram-negative bacteria are known to produce two types of surface organelles: flagella, which are required for motility and chemotaxis, and pili (fimbriae), which play a part in the interaction of bacteria with other bacteria and with eukaryotic host cells. Here we report a third class of E. coli surface organelles for which we propose the name curli. Curli are coiled surface structures composed of a single type of subunit, the curlin, which differs from all known pilin proteins and is synthesized in the absence of a cleavable signal peptide. Although the gene encoding this structural subunit, crl, is present and transcribed in most natural isolates of E. coli, only certain strains are able to assemble the subunit protein into curli. This assembly process occurs preferentially at growth temperatures below 37 degrees C. The ability of curli to mediate binding to fibronectin may be a virulence-associated property for wound colonization and for the colonization of fibronectin-coated surfaces.

  • 26.
    Paul-Satyaseela, M
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Karched, M
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Bian, Z
    Ihalin, R
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Chen, C
    Asikainen, Sirkka
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Immunoproteomics of Actinobacillus actinomycetemcomitans outer-membrane proteins reveal a highly immunoreactive peptidoglycan-associated lipoprotein.2006Ingår i: Journal of Medical Microbiology, ISSN 0022-2615, E-ISSN 1473-5644, Vol. 55, nr 7, s. 931-942Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a search for novel bioactive cell surface structures of periodontal pathogens, it was found that sera from two patients with Actinobacillus actinomycetemcomitans-associated infections reacted strongly at 17 kDa on immunoblots of A. actinomycetemcomitans outer-membrane protein (OMP) preparations. The 17 kDa antigen was also recognized by anti-CsgA (Escherichia coli curli major subunit) antibody. The 17 kDa A. actinomycetemcomitans protein was identified as peptidoglycan-associated lipoprotein (PAL; AaPAL) by two-dimensional immunoblotting and subsequent sequence analysis by mass spectrometry and bioinformatics tools. AaPAL was an OMP and a lipoprotein, and it had an OmpA-like domain. In a group of middle-aged subjects (n = 26), serum reactivity to AaPAL was associated with the presence of periodontitis but not with the oral detection of A. actinomycetemcomitans. Both human sera and rabbit antisera against three different types of antigens, the gel-purified AaPAL, A. actinomycetemcomitans whole-cell antigens, and CsgA, recognized putative PALs of oral haemophili in addition to AaPAL. The results demonstrated that the novel AaPAL is a conserved bacterial lipoprotein. It is expressed in vivo and is strongly immunoreactive. The antigenic cross-reactivity found between AaPAL and oral haemophili may enhance local and systemic immuno-inflammatory reactions in periodontitis.

  • 27.
    Petzold, Katja
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Olofsson, Annelie
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jürgen, Schleucher
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Semiconstant-Time P,H-COSY NMR: Analysis of Complex Mixtures of Phospholipids Originating from Helicobacter pylori2009Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, nr 40, s. 14150-1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lipids play a central role in numerous biological events, ranging from normal physiological processes to host−pathogen interactions. The proposed semiconstant-time 31P,1H−COSY NMR experiment provides identification of known and structural characterization of unknown phospholipids in complex membrane extracts with high sensitivity, based on the combination of their 1H and 31P chemical shifts and coupling patterns. Furthermore, the spectra allow quantification of phospholipid composition. Analysis of the phospholipid composition of Helicobacter pylori, the causative agent of peptic ulcer disease, showed the presence of uncommon phospholipids. This novel NMR approach allows the study of changes in membrane composition in response to biological stimuli and opens up the possibility of identifying soluble phosphorus species in a number of research fields.

  • 28. Skoog, Emma C.
    et al.
    Padra, Medea
    Åberg, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Obi, Ikenna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Quintana-Hayashi, Macarena P.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Linden, Sara K.
    BabA dependent binding of Helicobacter pylori to human gastric mucins cause aggregation that inhibits proliferation and is regulated via ArsS2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 40656Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mucins in the gastric mucus layer carry a range of glycan structures, which vary between individuals, can have antimicrobial effect or act as ligands for Helicobacter pylori. Mucins from various individuals and disease states modulate H. pylori proliferation and adhesin gene expression differently. Here we investigate the relationship between adhesin mediated binding, aggregation, proliferation and adhesin gene expression using human gastric mucins and synthetic adhesin ligand conjugates. By combining measurements of optical density, bacterial metabolic activity and live/dead stains, we could distinguish bacterial aggregation from viability changes, enabling elucidation of mechanisms behind the anti-prolific effects that mucins can have. Binding of H. pylori to Leb-glycoconjugates inhibited the proliferation of the bacteria in a BabA dependent manner, similarly to the effect of mucins carrying Leb. Furthermore, deletion of arsS lead to a decrease in binding to Leb-glycoconjugates and Leb-decorated mucins, accompanied by decreased aggregation and absence of anti-prolific effect of mucins and Leb-glycoconjugates. Inhibition of proliferation caused by adhesin dependent binding to mucins, and the subsequent aggregation suggests a new role of mucins in the host defense against H. pylori. This aggregating trait of mucins may be useful to incorporate into the design of adhesin inhibitors and other disease intervention molecules.

  • 29. Turkina, Maria V.
    et al.
    Olofsson, Annelie
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Magnusson, Karl-Eric
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Vikstrom, Elena
    Helicobacter pylori vesicles carrying CagA localize in the vicinity of cell-cell contacts and induce histone H1 binding to ATP in epithelial cells2015Ingår i: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 362, nr 11, artikel-id fnv076Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Helicobacter pylori produces outer membrane vesicles (OMV), delivering bacterial substances including the oncogenic cytotoxin-associated CagA protein to their surroundings. We investigated the effects of H. pylori OMV carrying CagA (OMV-CagA) on cell junctions and ATP-binding proteome of epithelial monolayers, using proteomics, mass spectrometry and imaging. OMV-CagA localized in close vicinity of ZO-1 tight junction protein and induced histone H1 binding to ATP. We suggest the expression of novel events in the interactions between H. pylori OMV and epithelia, which may have an influence on host gene transcription and lead to different outcomes of an infection and development of cancer.

  • 30. Yamaoka, Y
    et al.
    Ojo, O
    Fujimoto, S
    Odenbreit, S
    Haas, R
    Gutierrez, O
    El-Zimaity, H M T
    Reddy, R
    Arnqvist, Anna
    Umeå universitet, Medicinsk fakultet, Medicinsk kemi och biofysik.
    Graham, D Y
    Helicobacter pylori outer membrane proteins and gastroduodenal disease.2006Ingår i: Gut, ISSN 0017-5749, Vol. 55, nr 6, s. 775-81Artikel i tidskrift (Refereegranskat)
  • 31. Yamaoka, Yoshio
    et al.
    Souchek, Julianne
    Odenbreit, Stefan
    Haas, Rainer
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Kodama, Tadashi
    Osato, Michael S
    Gutierrez, Oscar
    Kim, Jong G
    Graham, David Y
    Discrimination between cases of duodenal ulcer and gastritis on the basis of putative virulence factors of Helicobacter pylori.2002Ingår i: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 40, nr 6, s. 2244-2246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The BabA, cagA, and vacA statuses of 827 Helicobacter pylori isolates were used in logistic regression models to discriminate duodenal ulcer from gastritis. Only BabA was a candidate for a universal virulence factor, but the low c statistic value (0.581) indicates that none of these factors were helpful in predicting the clinical presentation.

  • 32.
    Åberg, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    The Helicobacter pylori sialic acid binding adhesin SabA is regulated via a network of two-component systemsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The acid-responsive signaling system ArsRS plays a key role in regulating factors important for survival in acidic conditions during infection of the human stomach by Helicobacter pylori. In addition, ArsRS was suggested to control the disease-associated attachment protein SabA, however, mechanistic data is still lacking. We show that the repressing effect of the ArsRS system on SabA expression occurs both at acidic and neutral conditions and is mediated at the transcriptional level. Purified His6-ArsR binds PsabA DNA at several sites, with varying affinity and independent of phosphorylation status and H. pylori strains showed unique cognate PsabA sequences to tweak the ArsR binding ability, resulting in strain-dependent repression of SabA expression. By site-directed mutagenesis we reveal key amino acids for the binding activity of ArsR. Finally, we show that that ArsR binds to A/T-rich DNA as dimers or larger multimers, suggesting that ArsR has affinity for DNA structures rather than to a specific promoter DNA sequence. SabA expression is further influenced by the FlgRS and CrdRS two-component systems, illustrating a complicated crosstalk among regulatory networks in H. pylori.

  • 33.
    Åberg, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Gideonsson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Olofsson, Annelie
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Öhman, Carina
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Rakhimova, Lena
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Engstrand, Lars
    Brännström, Kristoffer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    A Repetitive DNA Element Regulates Expression of the Helicobacter pylori Sialic Acid Binding Adhesin by a Rheostat-like Mechanism2014Ingår i: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 10, nr 7, artikel-id e1004234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During persistent infection, optimal expression of bacterial factors is required to match the ever-changing host environment. The gastric pathogen Helicobacter pylori has a large set of simple sequence repeats (SSR), which constitute contingency loci. Through a slipped strand mispairing mechanism, the SSRs generate heterogeneous populations that facilitate adaptation. Here, we present a model that explains, in molecular terms, how an intergenically located T-tract, via slipped strand mispairing, operates with a rheostat-like function, to fine-tune activity of the promoter that drives expression of the sialic acid binding adhesin, SabA. Using T-tract variants, in an isogenic strain background, we show that the length of the T-tract generates multiphasic output from the sabA promoter. Consequently, this alters the H. pylori binding to sialyl-Lewis x receptors on gastric mucosa. Fragment length analysis of post-infection isolated clones shows that the T-tract length is a highly variable feature in H. pylori. This mirrors the host-pathogen interplay, where the bacterium generates a set of clones from which the best-fit phenotypes are selected in the host. In silico and functional in vitro analyzes revealed that the length of the T-tract affects the local DNA structure and thereby binding of the RNA polymerase, through shifting of the axial alignment between the core promoter and UP-like elements. We identified additional genes in H. pylori, with T- or A-tracts positioned similar to that of sabA, and show that variations in the tract length likewise acted as rheostats to modulate cognate promoter output. Thus, we propose that this generally applicable mechanism, mediated by promoter-proximal SSRs, provides an alternative mechanism for transcriptional regulation in bacteria, such as H. pylori, which possesses a limited repertoire of classical trans-acting regulatory factors.

  • 34.
    Öhman, Carina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Vallström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Olofsson, Annelie
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Johansson, Pär
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Larsson, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Aspholm, Marina
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Arnqvist, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Phase variation and expression mechanisms of the sialic acid binding adhesin SabA in Helicobacter pyloriManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Bacterial attachment to host epithelial surfaces by means of bacterial adhesion proteins is a key event in colonization. Phase variation is a mechanism used by bacteria that mediates frequent and reversible gains and losses in expression of proteins. In the inflamed stomach, H. pylori adherence to sialyl Lewis antigens (sLex) is mediated by the sialic acid binding adhesin (SabA). Instability in sLex-binding was previously reported and here we show that this is caused by the high frequency of ON/OFF switching in SabA expression. Our data shows that SabA phase variation is due to slippages in the number of CT repeat sequences in the 5’ end of the sabA gene (i.e. slipped strand mispairing). The sabA operon was defined and the sabA transcriptional start site was determined. Changes in the number of thymine bases present in a mononucleotide stretch upstream of the sabA gene and in close proximity to a -35-like promoter element did not affect the ON/OFF phase variation. Instead, we show that changes in intrinsic DNA properties are likely to influence SabA expression. The effect of growth phase on sLex-binding properties and SabA expression was also analyzed. SabA expression and sLex-binding increased as H. pylori entered late logarithmic phase. Our data show the ability of H. pylori to cycle between an adherent and non-adherent phenotype by phase variation mechanisms and adjustment of receptor binding activity. These data increase our understanding of how H. pylori adjust adherence properties during persistent infection.

1 - 34 av 34
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf