Lecture 11 - Bacterial Cell-Cell spread Flashcards Preview

Bacteriology > Lecture 11 - Bacterial Cell-Cell spread > Flashcards

Flashcards in Lecture 11 - Bacterial Cell-Cell spread Deck (29):
1

Advantages to intracellular pathogenesis
1)
2)
3)
4)
5)

1) Privileged environment (no competition)
2) Inaccessible to attack by complement, antibodies
3) No need to adhere to host cell
4) Readily available nutrients
5) Necessary, if obligate intracellular pathogen

2

What is a chemoheterotroph?

Organisms that use carbon sources as energy.

EG: Compounds from host cell interior

3

Intracellular niches
1)
2)
3)

1) Intralysosomal (low pH, hydrolytic)
2) Intravacuolar (neutral pH)
3) Cytosolic

4

Professional phagocytic cells

Macrophages, neutrophils, dendritic cells (kind of)

5

Which niche does Listeria live in?

Intracellular, cytosolic

6

How does Shigella escape vacuoles?

Phospholipases digest vacuole membrane

7

How does Shigella cause macrophages to undergo apoptosis?

Stimulate inflammosomes
Causes pro-caspase 1 activation, IL-1b, IL-18 release, pyroptosis

8

Shigella protein used for actin recruitment

IcsA

9

Which bacteria is IcsA found in?

Shigella

10

Protein type of IcsA

Autotransporter

11

IcsA function
1)
2)
3)

1) Binds N-WASP to glysine-rich region
2) N-WASP has two binding grooves, one for monomeric actin, one for Arp2/3 complex
3) Arp2/3 complex nucleates actin, actin chain begins formation

12

N-WASP interaction domains
1)
2)
3)
4)

1) CDC42
2) Nck
3) Actin
4) Arp2/3

13

Which part of IcsA binds N-WASP?

Glycine-rich region

14

What does the glycine-rich region of IcsA do?

Recruit N-WASP

15

N-WASP function
1)
2)

1) Has binding site for monomeric actin, Arp2/3
2) Supplies monomeric actin to Arp2/3

16

Protein expressed by Listeria for intracellular motility

ActA

17

What is ActA?

Protein expressed by Listeria
Causes polar actin polymerisation

18

Differences between ActA and IcsA
1)
2)
3)
4)

1) Acta is used by Listeria, IcsA by Shigella
2) ActA recruits VASP, IcsA recruits N-WASP
3) IcsA recruits actin at pole from start. ActA initially recruits actin all over cell, then begins recruiting polarly
4) ActA directly recruits VASP, actin and Arp2/3. IcsA recruits N-WASP, which then recruits actin and Arp2/3

19

What are LLO and phospholipase C?

Used by Listeria to digest vacuole wall

20

What does Listeria use to digest vacuolar wall?

LLO
Phospholipase C

21

Proteins recruited by IcsA

1) N-WASP
2) N-WASP recruits monomeric actin, Arp2/3

22

Proteins recruited by ActA

VASP, monomeric actin, Arp2/3

23

Other bacteria which recruit actin intracellularly
1)
2)

1) Ricketsia conorii
2) Burkholderia pseudomallei

24

Do R. conorii and B. pseudomallei use actin polymerisation as efficiently as Shigella and Listeria?

No

25

Advantages to living in macrophages
1)
2)
3)

1) Professional phagocytes, so easy to enter cell
2) Long-lived
3) Migrate through the body, so can help with dissemination

26

Oxygen-dependent killing

Respiratory burst using NADPH oxidase
Generates radical oxygen species
EG: H2O2, OCl-, O2-

27

Oxygen-independent killing
1)
2)
3)
4)
5)

1) Low pH (in lysosome)
2) Proteolytic enzymes
3) Lysozyme
4) Lactoferrin
5) Membrane-damaging proteins

28

Vesicles involved in phagosome maturation
1)
2)
3)

1) Early endosome
2) Late endosome
3) Lysosome

29

By which mechanism do EE, LE and Ly help in phagosome maturation?

Kiss and run