Secretion systems Flashcards Preview

ZZPathology undergraduate year 3, first term. > Secretion systems > Flashcards

Flashcards in Secretion systems Deck (25):
1

Type I substrate

proteins, including RTX toxins, cell surface layer proteins, proteases, lipases, bacteriocins, heme acquisition proteins and etc. , drugs

2

Type II substrate

signal peptide containing precursor proteins. Folded proteins.

3

Type IV substrate

 DNA – for conjugation
 proteins, protein complexes, nucleoprotein complexes.

4

Type I pumping mechanism

can be primary (ABC) or secondary (SMR, MATE, etc)

5

Type II pumping mechanism

Sec translocon binds precursor. Leader peptidase (e.g. peptidase GspOa?) cleaves signal peptide and the protein is released into the periplasm. Powered by an NTPase. This is the general export pathway.
 Tat can be used rather than Sec; Pseudomonas exports phospholipases this way. Signal peptides have a twin arginine motif.

6

Type V pumping mechanism

No energy coupling or accessory proteins.

7

Type I across the inner membrane

pump protein

8

Type IV across the inner membrane

 Core complex spans both inner and outer membrane. Made fro VirB7, VirB9 and VirB10. Self assembling

9

Type V across the inner membrane.

 N terminal leader initiates inner membrane transport.

10

Across the periplasm: Type I

TolC, adaptors.

11

Across the periplasm: Type IV

 Core complex spans both inner and outer membrane. Made fro VirB7, VirB9 and VirB10. Self assembling

12

Across the outer membrane: type I

TolC

13

Across the outer membrane: type II

2 proteins located in OM.

14

Across the outer membrane: type IV

 Core complex spans both inner and outer membrane. Made fro VirB7, VirB9 and VirB10. Self assembling.

15

Across the outer membrane: type V

 C terminal helper domain necessary.
 IgA1 protease cleaves away from membrane bound sequence

16

Purpose of type I

export of toxins, other proteins and drugs.

17

Purpose of type II

main terminal branch of General secretory pathway.

18

Purpose of type II

delivery of proteins by
 Yersinia
 Salmonella
 Shigella
 Bordetella
 Pseudomonas.
Also used in type IV pilus formation.

19

Purpose of type IV

 Conjugation
 Virulence protein injection (H. Pylori, Brucella suis, Legionella pneumophila) and secretion (Bordetella pertussis)
 Mediating DNA release and uptake (H. Pylori, Neisseria gonorrhoeae)

20

Purpose of type V

 Autotransporters
 2 partner system
 Vc or AT-2

21

Type IV pilus structure

Tip adhesin
Major pilus subunit
Base of structure
Other

22

Type IV tip adhesin

• P. Aeruginosa tip adhesin PilY1 binds asialoGM1/2
• Neisseria tip adhesin binds CD46

23

Type IV major pilus subunit

PilA

24

Type IV base of structure

• PilQ = channel in OM
• PilC essential inner membrane protein
• PilB energises assembly via hydrolysis of NTPs.
• PilT energises retraction and recycling of pilins.

25

Type IV pilus structure - other

• PilD is a specific peptidase on the inner membrane, cleaves signal peptide for Sec pathway on secreted proteins.