Lecture 7. Pili/Fimbriae and Endospores, Infectious Disease Statistics Flashcards
What are type 1 fimbriae?
Important virulence factor in a range of pathogens
Thin, 7 nm wide and approximately 1-2 µm long surface polymer
Bulk is made up of 500-3000 subunits of the protein, FimA, stacked in a helical cylinder
Where is FimH found and what does it do?
Found in the tip adhesin
Binds to D-mannose containing structures
What do FimF and FimG do?
Link FimH adhesin onto the fimbriae
What does FimC do?
Chaperone
What does FimA do?
Usher protein, catalyses FimA polymerisation at base of pili
What is P-pili?
Also known as PAP: Pyelonephritis-Associated-Pili
Critical virulence factor of uropathogenic E. coli (UPEC) which cause cystitis and pyelonephritis
Similar in structure and assembly to type I fimbriae
What are type IV pili?
Widely distributed in Gram negatives
Typically longer than fimbriae
Often aggregate laterally to form bundles
Variety of roles (Host cell adhesion, biofilm formation (EPEC) twitching motility, crawl along a surface enable enteropathogenic E. coli (EPEC) to form microcolonies on tissue monolayers
What are many pathogens?
Species specific
Specificity of E. coli pathogens is determined by LPS (O antigen) and fimbriae (K antigen)
CFA (colonising factor antigen) fimbriae are present on E. coli pathogenic to humans
What have specific interactions with mucosal epithelium?
Enterotoxigenic E. coli (ETEC) strains via CFA (colony factor antigen)
Non-pathogenic strains do not possess CFA
Where are F pilus found?
Only found in Gram negative bacteria
What are F pilus involved with?
Transfer of genetic information
What occurs in the process of conjugation?
- Attachment F+ donor to F- donor
- Retraction
- Exchange (plasmid transferred)
- Transformation both F+ cells
What are bacterial endospores?
Dormant stage in bacterial life cycle
Called endospores because they form inside bacterial cell
What bacteria produce endospores?
Only Gram positive
How do bacterial endospores form?
When a vegetative cell becomes stressed
