Surface proteins of Finegoldia magna interacting with the human host

Research output: ThesisDoctoral Thesis (compilation)

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Abstract

Finegoldia magna is a Gram-positive anaerobe and a member of the normal human microflora. This bacterium is also an opportunistic pathogen and isolated from ~10% of all anaerobic infections. Reoccurring taxonomical changes and the anaerobic growth have contributed to the neglect of F. magna. The present thesis describes the identification and characterization of two novel surface proteins of F. magna.

One of the identified proteins, SufA, is a protease belonging to the subtilase family. This protease cleaves and inactivates the antimicrobial peptide LL-37 and the antibacterial chemokine MIG/CXCL9. Furthermore, the protease cleaves fibrinogen and thereby inhibits fibrin network formation. To our knowledge, the first example of directed mutagenesis of F. magna is presented with the disruption of the sufA gene.

The other identified protein is FAF. This is a cell wall attached α-helical protein that forms hair-like projections on the bacterial surface. FAF is self-associating and contributes to bacterial clumping. FAF also mediates adhesion of the bacterium to basement membranes of human skin by interacting with BM-40. A further function of FAF is blocking of the activity of antimicrobial peptides. The genes encoding faf and sufA are present in a majority of investigated isolates indicating that the proteins have important functions.

In conclusion, the findings presented in this thesis may help explain how F. magna colonizes the human host and causes opportunistic infections.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Infection Medicine (BMC)
Supervisors/Advisors
  • Frick, Inga-Maria, Supervisor
  • Björck, Lars, Supervisor
  • Collin, Mattias, Supervisor
Award date2008 Dec 19
Publisher
ISBN (Print)978-91-86059-87-3
Publication statusPublished - 2008

Bibliographical note

Defence details

Date: 2008-12-19
Time: 09:15
Place: Rune Grubb-salen, Biomedicinskt Centrum, Sölvegatan 18, 22184 Lund

External reviewer(s)

Name: O'Toole, Paul W.
Title: Dr
Affiliation: Department of Microbiology & Alimentary Pharmabiotic Centre, University College Cork, Ireland

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This thesis is based on the following papers (I-IV).

I. SufA -a novel subtilisin-like serine proteinase of Finegoldia magna
Karlsson, C., Andersson, M-L., Collin, M., Schmidtchen, A., Björck, L.,
Frick, I-M.
Microbiology, 2007, 153: 4208-18

II. SufA – a bacterial enzyme that cleaves fibrinogen and blocks fibrin network formation
Karlsson, C., Mörgelin, M., Collin, M., Lood, R., Andersson, M-L.,
Schmidtchen, A., Björck, L,. Frick, I-M.
Microbiology Accepted

III. Identification of a novel protein promoting the colonization and survival of Finegoldia magna, a bacterial commensal and opportunistic pathogen
Frick, I-M., Karlsson, C., Mörgelin, M., Olin, A., Janjusevic, R.,
Hammarström, C., Holst, E., de Château, M., Björck, L.
Mol Microbiol, 2008, 70: 695 – 708

IV. SufA, a serine-protease of Finegoldia magna, enhances bacterial survival by modulating activities of the antibacterial chemokine MIG/CXCL9.
Karlsson, C.*, Eliasson, E.*, Olin, A, Mörgelin, M., Karlsson, A., Egesten,
A., Frick, I-M.
Manuscript

*indicates these authors as equally contributing

Subject classification (UKÄ)

  • Infectious Medicine

Free keywords

  • Finegoldia magna
  • Gram-positive anaerobic cocci
  • surface proteins
  • protease
  • LL-37
  • MIG/CXCL9
  • Fibrinogen
  • adhesion
  • gene disruption
  • bacterial aggregation
  • basement membranes

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