umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Detection of functional P fimbriae proteins in E. coli outer membrane vesicles
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Bernt Eric Uhlin)
Organic Chemistry, Lund University.
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Bernt Eric Uhlin)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Outer membrane vesicles (OMVs) are continuously released from the surface of Gram negative bacteria. The composition of the OMVs is similar to that of the outer membrane and may include periplasmic constituents. Studies have shown that OMVs also may have a role in the delivery of bacterial toxins to the extracellular space. Results: In this study we investigate the association of P fimbriae proteins to OMVs from both genetically manipulated E. coli laboratory strains and a uropathogenic isolate. We found that the OMVs could carry functionally active P fimbriae proteins on their surface and we observed specific attachment of OMVs to beads coated with the P fimbrial galabiose receptor. Conclusions: Our results suggest that OMVs can carry functionally active fimbrial proteins on their surface and that they may have a role in specific delivery of bacterial components to target cells.

Keyword [en]
Eshcerichia coli, outer membrane vesicles, OMVs, P fimbriae, adhesion
National Category
Microbiology in the medical area
Research subject
Molecular Biology
Identifiers
URN: urn:nbn:se:umu:diva-27737OAI: oai:DiVA.org:umu-27737DiVA: diva2:277440
Available from: 2009-11-18 Created: 2009-11-18 Last updated: 2009-11-26Bibliographically approved
In thesis
1. Molecular analysis of transcription factors in uropathogenic E. coli adhesin operons
Open this publication in new window or tab >>Molecular analysis of transcription factors in uropathogenic E. coli adhesin operons
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Molekylär analys av transkriptionsfaktorer i adhesin operon hos uropatogena E. coli
Abstract [en]

The main causative agent of human urinary tract infections is the uropathogenic Escherichia coli (UPEC) pathotype. It may cause disease due to its ability to express a number of bacterial virulence factors. Fimbrial adhesins are particularly important for the initial establishment of infection in the urinary tract. The fimbriae are hair-like structures protruding from the bacterial cell and by attaching to specific receptors in the urinary tract they mediate adherence to different cell types, allowing the bacteria to resist the shear forces from urine flow. The UPEC strains generally carry multiple determinants for fimbrial adhesins. Previous studies have indicated that there is a co-regulation between different fimbrial genes and one factor that has been implicated in this is the PapB protein, acting as a transcriptional regulator of P-fimbrial expression. The PapB protein can be regarded as the prototype of a family of fimbrial regulators that show high homology between different fimbrial operons. One homolog is FocB, regulator of F1C fimbriae. In this study, the role of the FocB protein in the regulation of F1C fimbriae as well as in the co-regulation with other fimbrial genes was investigated. It was observed that FocB binds to DNA, similarly to PapB, in an oligomeric fashion and that PapB and FocB can form hetero-oligomeric complexes, which appear to have a repressive role in the regulation of the F1C fimbriae. In addition, the FocB protein also had a repressive effect on transcription of the fim operon, which encodes theType 1 fimbriae. For further analysis of FocB in vitro, we developed efficient procedures for purification of the protein and established conditions for its crystal formation with the aim to conduct X-ray diffraction studies. By the hanging-drop vapour-diffusion method, we obtained crystals that in the X-ray analysis diffracted sufficiently well to allow modelling of a high resolution structure of FocB. The structural model was considered in relation to the DNA binding properties of the protein. The FocB analysis represents the first structural model of this family of transcriptional factors. This model should aid in further understanding of the roles and functions of these proteins in the regulation of the UPEC fimbrial operons. The complexity of the system, with multiple factors involved in the regulation of fimbrial operons, was revealed in earlier studies of the PapI protein showing that PapI activates transcription of the pap operon as a part of a complex with the global regulator Lrp. However, PapI itself did not appear to bind to DNA and its mode of action has remained unclear. By genetic analyses and in vitro studies we show that PapI may interact also with the α subunit of the RNA polymerase. This finding indicates that PapI might directly interact with the transcriptional apparatus and thus aid in the activation of pap expression. Bacteria are frequently releasing outer membrane vesicles (OMVs) from their surface. We studied the release of the haemolysin toxin from E. coli in connection with formation of OMVs and found that the toxin was tightly associated with the vesicles in an active form. By overproduction of the PapB or PapI regulators in order to maximise the population of bacteria expressing fimbriae, we could detect P fimbriae proteins associated with OMVs that displayed specific adhesion to receptor-coated beads. This suggests a possible scenario in which the vesicles canfunction as directed vehicles of bacterial virulence factors.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2009. 63 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1304
Keyword
UPEC, E. coli, F1C, P fimbriae, cross-talk, FocB, PapB, crystal structure, OMVs
National Category
Microbiology in the medical area
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-27757 (URN)978-91-7264-879-1 (ISBN)
Public defence
2009-12-16, Major Groove, Institutionen för Molekylärbiologi, Byggn. 6L, Norrlands Universitetssjukhus, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2009-11-26 Created: 2009-11-19 Last updated: 2011-04-28Bibliographically approved

Open Access in DiVA

No full text

By organisation
Molecular Biology (Faculty of Medicine)
Microbiology in the medical area

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 116 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf