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Sjöström, Annika E
Alternative names
Publications (8 of 8) Show all publications
Aung, K. M., Sjöström, A. E., von Pawel-Rammingen, U., Riesbeck, K., Uhlin, B. E. & Wai, S. N. (2016). Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U. Journal of Innate Immunity, 8(3), 269-283
Open this publication in new window or tab >>Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U
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2016 (English)In: Journal of Innate Immunity, ISSN 1662-811X, E-ISSN 1662-8128, Vol. 8, no 3, p. 269-283Article in journal (Refereed) Published
Abstract [en]

Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.

Keywords
Vibrio cholerae, Outer membrane vesicles, Outer membrane protein U, Serum resistance, Naturally occurring IgG antibodies, C1q
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-118731 (URN)10.1159/000443646 (DOI)000375803900006 ()26934383 (PubMedID)
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2018-06-07Bibliographically approved
Sjöström, A. E., Sandblad, L., Uhlin, B. E. & Wai, S. N. (2015). Membrane vesicle-mediated release of bacterial RNA. Scientific Reports, 5, Article ID 15329.
Open this publication in new window or tab >>Membrane vesicle-mediated release of bacterial RNA
2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 15329Article in journal (Refereed) Published
Abstract [en]

Many Gram-negative bacterial species release outer membrane vesicles (OMVs) that interact with the host by delivering virulence factors. Here, we report for the first time that RNA is among the wide variety of bacterial components that are associated with OMVs. To characterize the RNA profiles of bacterial OMVs, we performed RNA deep sequencing analysis using OMV samples isolated from a wild type Vibrio cholerae O1 El Tor strain. The results showed that RNAs originating from intergenic regions were the most abundant. Our findings reveal a hitherto unrecognised feature of OMVs mimicking eukaryotic exosomes and highlight a need to evaluate the potential role of RNA-containing bacterial membrane vesicles in bacteria-host interactions.

Place, publisher, year, edition, pages
Nature Publishing Group, 2015
National Category
Microbiology in the medical area
Identifiers
urn:nbn:se:umu:diva-111144 (URN)10.1038/srep15329 (DOI)000363031300001 ()26483327 (PubMedID)
Available from: 2015-11-12 Created: 2015-11-06 Last updated: 2018-06-07Bibliographically approved
Song, T., Sabharwal, D., Gurung, J. M., Cheng, A. T., Sjöström, A. E., Yildiz, F. H., . . . Wai, S. N. (2014). Vibrio cholerae Utilizes Direct sRNA Regulation in Expression of a Biofilm Matrix Protein. PLoS ONE, 9(7), Article ID e101280.
Open this publication in new window or tab >>Vibrio cholerae Utilizes Direct sRNA Regulation in Expression of a Biofilm Matrix Protein
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2014 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 7, article id e101280Article in journal (Refereed) Published
Abstract [en]

Vibrio cholerae biofilms contain exopolysaccharide and three matrix proteins RbmA, RbmC and Bap1. While much is known about exopolysaccharide regulation, little is known about the mechanisms by which the matrix protein components of biofilms are regulated. VrrA is a conserved, 140-nt sRNA of V. cholerae, whose expression is controlled by sigma factor sigma(E). In this study, we demonstrate that VrrA negatively regulates rbmC translation by pairing to the 5' untranslated region of the rbmC transcript and that this regulation is not stringently dependent on the RNA chaperone protein Hfq. These results point to VrrA as a molecular link between the sigma(E)-regulon and biofilm formation in V. cholerae. In addition, VrrA represents the first example of direct regulation of sRNA on biofilm matrix component, by-passing global master regulators.

Place, publisher, year, edition, pages
PLOS, 2014
National Category
Cell and Molecular Biology Infectious Medicine Microbiology in the medical area
Identifiers
urn:nbn:se:umu:diva-92947 (URN)10.1371/journal.pone.0101280 (DOI)000339614100012 ()
Available from: 2014-09-15 Created: 2014-09-09 Last updated: 2018-06-07Bibliographically approved
Duperthuy, M., Sjöström, A. E., Sabharwal, D., Damghani, F., Uhlin, B. E. & Wai, S. N. (2013). Role of the Vibrio cholerae Matrix Protein Bap1 in Cross-Resistance to Antimicrobial Peptides. PLoS Pathogens, 9(10), e1003620
Open this publication in new window or tab >>Role of the Vibrio cholerae Matrix Protein Bap1 in Cross-Resistance to Antimicrobial Peptides
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2013 (English)In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 9, no 10, p. e1003620-Article in journal (Refereed) Published
Abstract [en]

Outer membrane vesicles (OMVs) that are released from Gram-negative pathogenic bacteria can serve as vehicles for the translocation of effectors involved in infectious processes. In this study we have investigated the role of OMVs of the Vibrio cholerae O1 El Tor A1552 strain in resistance to antimicrobial peptides (AMPs). To assess this potential role, we grew V. cholerae with sub-lethal concentrations of Polymyxin B (PmB) or the AMP LL-37 and analyzed the OMVs produced and their effects on AMP resistance. Our results show that growing V. cholerae in the presence of AMPs modifies the protein content of the OMVs. In the presence of PmB, bacteria release OMVs that are larger in size and contain a biofilm-associated extracellular matrix protein (Bap1). We demonstrated that Bap1 binds to the OmpT porin on the OMVs through the LDV domain of OmpT. In addition, OMVs from cultures incubated in presence of PmB also provide better protection for V. cholerae against LL-37 compared to OMVs from V. cholerae cultures grown without AMPs or in presence of LL-37. Using a bap1 mutant we showed that cross-resistance between PmB and LL-37 involved the Bap1 protein, whereby Bap1 on OMVs traps LL-37 with no subsequent degradation of the AMP.

National Category
Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-86637 (URN)10.1371/journal.ppat.1003620 (DOI)000330383800011 ()
Available from: 2014-04-24 Created: 2014-03-03 Last updated: 2018-06-07Bibliographically approved
Castelain, M., Sjöström, A. E., Fällman, E., Uhlin, B. E. & Andersson, M. (2010). Unfolding and refolding properties of S pili on extraintestinal pathogenic Escherichia coli. European Biophysics Journal, 39(8), 1105-1115
Open this publication in new window or tab >>Unfolding and refolding properties of S pili on extraintestinal pathogenic Escherichia coli
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2010 (English)In: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 39, no 8, p. 1105-1115Article in journal (Refereed) Published
Abstract [en]

S pili are members of the chaperone-usher-pathway-assembled pili family that are predominantly associated with neonatal meningitis (S(II)) and believed to play a role in ascending urinary tract infections (S(I)). We used force-measuring optical tweezers to characterize the intrinsic biomechanical properties and kinetics of S(II) and S(I) pili. Under steady-state conditions, a sequential unfolding of the layers in the helix-like rod occurred at somewhat different forces, 26 pN for S(II) pili and 21 pN for S(I) pili, and there was an apparent difference in the kinetics, 1.3 and 8.8 Hz. Tests with bacteria defective in a newly recognized sfa gene (sfaX (II)) indicated that absence of the sfaX (II) gene weakens the interactions of the fimbrium slightly and decreases the kinetics. Data of S(I) are compared with those of previously assessed pili primary associated with urinary tract infections, the P and type 1 pili. S pili have weaker layer-to-layer bonds than both P and type 1 pili, 21, 28 and 30 pN, respectively. In addition, the S pili kinetics are ~10 times faster than the kinetics of P pili and ~550 times faster than the kinetics of type 1 pili. Our results also show that the biomechanical properties of pili expressed ectopically from a plasmid in a laboratory strain (HB101) and pili expressed from the chromosome of a clinical isolate (IHE3034) are identical. Moreover, we demonstrate that it is possible to distinguish, by analyzing force-extension data, the different types of pili expressed by an individual cell of a clinical bacterial isolate.

Keywords
Fimbriae, uropathogenic escherichia coli, bond breaking, unfolding, optical tweezers
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-32913 (URN)10.1007/s00249-009-0552-8 (DOI)000279194500001 ()19885656 (PubMedID)
Available from: 2010-03-30 Created: 2010-03-30 Last updated: 2018-06-08Bibliographically approved
Sjöström, A. E., Sondén, B., Müller, C., Rydström, A., Dobrindt, U. & Uhlin, B. E. (2009). Analysis of the sfaXII locus in the Escherichia coli meningitis isolate IHE3034 reveals two novel regulatory genes within the promoter-distal region ofthe main S fimbrial operon. Microbial Pathogenesis, 46(3), 150-158
Open this publication in new window or tab >>Analysis of the sfaXII locus in the Escherichia coli meningitis isolate IHE3034 reveals two novel regulatory genes within the promoter-distal region ofthe main S fimbrial operon
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2009 (English)In: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 46, no 3, p. 150-158Article in journal (Refereed) Published
Abstract [en]

We describe the expression and regulation of the gene sfaXII located near the SfaII fimbrial determinant inthe newborn meningitis Escherichia coli (NMEC) isolate IHE3034. sfaXII belongs to a gene family, the 17-kDa 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 genefusions we found that different environmental conditions commonly affecting expression of fimbrialgenes also affected sfaXII expression. Analysis of the sfaXII transcripts showed that the gene is part of themain 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 downregulationby the nucleoid protein H-NS. Studies with an sfaXII mutant derivative of IHE3034 did notreveal 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 caninfluence 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.

Place, publisher, year, edition, pages
Elsevier Ltd, 2009
Keywords
NMEC, Regulation, Fimbrial genes, sfa operon
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-114402 (URN)
Available from: 2016-01-18 Created: 2016-01-18 Last updated: 2018-06-07
Sjöström, A. E., Balsalobre, C., Emödy, L., Westerlund-Wikström, B., Hacker, J. & Uhlin, B. E. (2009). The SfaXII protein from newborn meningitis E. coli is involved in regulation of motility and type 1 fimbriae expression. Microbial Pathogenesis, 46(5), 243-252
Open this publication in new window or tab >>The SfaXII protein from newborn meningitis E. coli is involved in regulation of motility and type 1 fimbriae expression
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2009 (English)In: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 46, no 5, p. 243-252Article in journal (Refereed) Published
Abstract [en]

The genomes of pathogenic E. coli may contain several different fimbrial operons. How bacteria regulate and coordinate the choice of fimbrial expression under different circumstances remains largely unanswered. In this report we have investigated the role of the sfaXII gene associated to the SfaII fimbrial determinant in the E. coli isolate IHE3034. sfaXII belongs to a subfamily of genes, the 17kDa genes, located near different fimbrial operons in uropathogenic and newborn meningitis E. coli (NMEC) strains. Using the NMEC isolate IHE3034 and non-pathogenic E. coli strains we found that the sfaXII gene had an inhibitory effect on type 1 fimbriae expression. Down regulation of type 1 fimbriae was exerted at transcriptional level both by inhibiting expression from the fimA promoter and by reducing the frequency of OFF-to-ON switching. The effect of sfaXII on expression of the recombinase FimB that catalyzes OFF to ON switching might explain the described reduction in percentage of ON cells. Moreover, expression of the sfaXII gene strongly influenced motility and flagella production of the NMEC isolate IHE3034. We propose that the sfaXII gene, and presumably other members in the 17kDa gene family, may play a role in the control of virulence related gene expression in pathogenic E. coli.

Place, publisher, year, edition, pages
Elsevier Ltd, 2009
Keywords
NMEC, Regulation, S fimbriae, Type 1 fimbriae, Motility
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-22286 (URN)10.1016/j.micpath.2009.01.007 (DOI)19486641 (PubMedID)
Available from: 2009-05-05 Created: 2009-05-04 Last updated: 2018-06-08Bibliographically approved
Sjöström, A. E. & Uhlin, B. E.Growth phase regulated expression of sfaXII is negatively influenced by the RpoS sigma factor and the Hfq RNA chaperone.
Open this publication in new window or tab >>Growth phase regulated expression of sfaXII is negatively influenced by the RpoS sigma factor and the Hfq RNA chaperone
(English)Manuscript (Other academic)
Abstract [en]

The regulatory gene sfaXII in the S fimbrial gene cluster of the newborn meningitis E. coli isolate IHE3034 is expressed in a growth phase dependent fashion with the highest levels at the onset of the stationary phase. It is then mainly transcribed from a promoter proximal to the gene. We have assessed the potential influence by the stationary phase sigma factor, σS, in the sfaXII regulation. In contrast to the stimulatory role commonly seen with stationary phase induced genes, we found that σS exerted a strong repressive effect on sfaXII transcription. Tests with an hfq mutant strain suggested that also the RNA chaperon Hfq caused negative regulation of sfaXII transcription. In both cases the effects were considered indirect via some other regulatory factor(s). Results from a transposon insertion mutagenesis experiment indicated that it may be possible to identify additional genes involved in sfaXII regulation.

National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-22281 (URN)
Available from: 2009-05-04 Created: 2009-05-04 Last updated: 2018-06-08Bibliographically approved
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