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  • 1.
    Johansson, J
    et al.
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Eriksson, S
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Sondén, B
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Wai, S N
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Uhlin, B E
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Heteromeric interactions among nucleoid-associated bacterial proteins: localization of StpA-stabilizing regions in H-NS of Escherichia coli.2001Ingår i: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 183, nr 7, s. 2343-2347Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nucleoid-associated proteins H-NS and StpA in Escherichia coli bind DNA as oligomers and are implicated in gene regulatory systems. There is evidence for both homomeric and heteromeric H-NS-StpA complexes. The two proteins show differential turnover, and StpA was previously found to be subject to protease-mediated degradation by the Lon protease. We investigated which regions of the H-NS protein are able to prevent degradation of StpA. A set of truncated H-NS derivatives was tested for their ability to mediate StpA stability and to form heteromers in vitro. The data indicate that H-NS interacts with StpA at two regions and that the presence of at least one of the H-NS regions is necessary for StpA stability. Our results also suggest that a proteolytically stable form of StpA, StpA(F21C), forms dimers, whereas wild-type StpA in the absence of H-NS predominantly forms tetramers or oligomers, which are more susceptible to proteolysis.

  • 2.
    Lindberg, Stina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Xia, Yan
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Sondén, Berit
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Göransson, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Hacker, Jörg
    Institut für Moleculare Infektionsbiologie, Würzburg, Germany.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Regulatory Interactions among adhesin gene systems of uropathogenic Escherichia coli2008Ingår i: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 76, nr 2, s. 771-780Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Uropathogenic Escherichia coli strain J96 carries multiple determinants for fimbrial adhesins. The regulatory protein PapB of P fimbriae has previously been implicated in potential coregulatory events. The focB gene of the F1C fimbria determinant is highly homologous to papB; the translated sequences share 81% identity. In this study we investigated the role of PapB and FocB in regulation of the F1C fimbriae. By using gel mobility shift assays, we showed that FocB binds to sequences in both the pap and foc operons in a somewhat different manner than PapB. The results of both in vitro cross-linking and in vivo oligomerization tests indicated that FocB could function in an oligomeric fashion. Furthermore, our results suggest that PapB and FocB can form heterodimers and that these complexes can repress expression of the foc operon. The effect of FocB on expression of type 1 fimbriae was also tested. Taken together, the results that we present expand our knowledge about a regulatory network for different adhesin gene systems in uropathogenic E. coli and suggest a hierarchy for expression of the fimbrial adhesins.

  • 3.
    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.

  • 4.
    Sjöström, Annika E.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Sondén, Berit
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Müller, Claudia
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Rydström, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Dobrindt, Ulrich
    Institute for Molecular Infection Biology, University of Würzburg, Germany.
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Analysis of the sfaXII locus in the Escherichia coli meningitis isolate IHE3034 reveals two novel regulatory genes within the promoter-distal region of the main S fimbrial operon2009Ingår i: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 46, nr 3, s. 150-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe the expression and regulation of the gene sfaXII located near the SfaII fimbrial determinant in the newborn meningitis Escherichia coli (NMEC) isolate IHE3034. sfaXII belongs to a gene family, the 17kDa genes, typically located downstream (300 – 3000 bp) of different fimbrial operons found in E. coli isolates of uropathogenic and newborn meningitis origin. Using transcriptional sfaXII reporter gene fusions we found that different environmental conditions commonly affecting expression of fimbrial genes also affected sfaXII expression. Analysis of the sfaXII transcripts showed that the gene is part of the main fimbrial operon as it is transcribed together with the rest of the fimbrial genes. In addition, the sfaXII gene can be expressed from a more proximal promoter and is found to be subject to strong down-regulation by the nucleoid protein H-NS. Studies with an sfaXII mutant derivative of IHE3034 did not reveal effects on SfaII fimbrial biogenesis as monitored by e.g. immunofluorescence microscopy. Nevertheless, a mutation in sfaXII resulted in altered expression of other surface components. Moreover, we define a new gene, sfaYII, coding for a putative phosphodiesterase that is located in between the sfaXII gene and the fimbrial biogenesis genes. Our studies by ectopic expression of sfaYII in Vibrio cholerae showed that the gene product caused reduced biofilm formation and it is proposed that sfaYII can influence cyclic-di-GMP turnover in the bacteria. Our findings demonstrate that the operons typical for S-fimbriae of extraintestinal pathogenic E. coli include previously unrecognized novel regulatory genes.

  • 5.
    Sondén, Berit
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Kocíncová, Dana
    Deshayes, Caroline
    Euphrasie, Daniel
    Rhayat, Lamya
    Laval, Françoise
    Frehel, Claude
    Daffé, Mamadou
    Etienne, Gilles
    Reyrat, Jean-Marc
    Gap, a mycobacterial specific integral membrane protein, is required for glycolipid transport to the cell surface.2005Ingår i: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 58, nr 2, s. 426-440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cell envelope of mycobacteria is a complex multilaminar structure that protects the cell from stresses encountered in the environment, and plays an important role against the bactericidal activity of immune system cells. The outermost layer of the mycobacterial envelope typically contains species-specific glycolipids. Depending on the mycobacterial species, the major glycolipid localized at the surface can be either a phenolglycolipid or a peptidoglycolipid (GPL). Currently, the mechanism of how these glycolipids are addressed to the cell surface is not understood. In this study, by using a transposon library of Mycobacterium smegmatis and a simple dye assay, six genes involved in GPLs synthesis have been characterized. All of these genes are clustered in a single genomic region of approximately 60 kb. We show by biochemical analyses that two non-ribosomal peptide synthetases, a polyketide synthase, a methyltransferase and a member of the MmpL family are required for the biosynthesis of the GPLs backbone. Furthermore, we demonstrate that a small integral membrane protein of 272 amino acids named Gap (gap: GPL addressing protein) is specifically required for the transport of the GPLs to the cell surface. This protein is predicted to contain six transmembrane segments and possesses homologues across the mycobacterial genus, thus delineating a new protein family. This Gap family represents a new paradigm for the transport of small molecules across the mycobacterial envelope, a critical determinant of mycobacterial virulence.

1 - 5 av 5
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