Lecture 12 - Intra-vacuolar Survival Flashcards Preview

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Flashcards in Lecture 12 - Intra-vacuolar Survival Deck (41)
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1
Q

How does phagosomal maturation occur?
1)
2)

A

1) Early, late endosomes and lysosomes in the cytoplasm
2) These kiss and run phagosomes, depending on which surface markers the phagosomes are displaying, and help mature phagosome

2
Q

Surface marker of late phagosome

A

LAMP-1

3
Q

How do phagosomal surface markers select specific endosomes?

A

Surface markers are SNARE proteins, EG: EEA1 (early endosome antigen 1)

4
Q

V-ATPase

A

Vacuolar ATPase
Present in membrane of late phagosome
H+ pump, decreases pH in late phagosome

5
Q

Which stage of vacuolar development does Mycobacterium live in?

A

Early endosome

6
Q

Which stage of vacuolar development does Salmonella live in?

A

Late endosome

7
Q

Which bacterium halts phagosomal development at early phagosome?

A

Mycobacterium

8
Q

Which bacterium halts phagosomal development at late endosome?

A

Salmonella

9
Q

Which bacterium lives in late phagosome?

A

Coxiella

10
Q

What does Coxiella burnetii cause?

A

Q fever

11
Q

Causative agent of Q fever

A

Coxiella burnetii

12
Q

Surface markers for late endosome

A

LAMP1, LAMP2, cathepsin D

13
Q

What is cathepsin D?

A

A protease

14
Q

Environment that Coxiella burnetii needs to replicate

A

Acidic

Below pH 5

15
Q

Close relative of Legionella

A

Coxiella burnetii

16
Q

Close relative of Coxiella

A

Legionella

17
Q

Secretion system used by Coxiella and Legionella

A

Type IV secretion system (Dot/Igm)

18
Q

Endosome always associated with macropinocytosis

A

Recycling endosome

19
Q

Filament produced by Salmonella in a vacuole

A

Salmonella induced filament (Sif)

20
Q

Where is Salmonella induced filament expressed?

A

Salmonella containing vacuole

21
Q

Phagosomal components missing in SCV
1)
2)
3)

A

1) Cation-independent mannose-6-phosphate receptor
2) Lysosomal enzymes
3) NADPH oxidase in phagosomal wall

22
Q

Which bacterium resides in a spacious phagosome?

A

Salmonella

23
Q

Which bacterium expresses SifA?

A

Salmonella

24
Q

Protein expressed by Salmonella to induce Sif formation

A

SifA

25
Q

Targets of SifA

A

Rab7

SKIP (mammalian kinesin binding protein)

26
Q

Kinesin

A

Protein involved in transporting vesicles along microtubules

27
Q

Movement of Salmonella-containig vesicle

A

From periphery down to near nucleus

28
Q

What encodes SifA?

A

SPI-2

29
Q

Which kind of pathogen is Legionella?

A

Facultative intracellular pathogen

30
Q

Human cell in which Legionella replicates

A

Alveolar macrophage

31
Q

How good is Legionella at avoiding human immune system?

A

Very poor.
Stimulates a strong immune response, normally doesn’t lead to infection. Only dangerous in the immunocompromised
Didn’t evolve to evade human immune system

32
Q

At which stage does Legionella halt phagosome formation?

A

Doesn’t even interact with early endosome.

Very, very early

33
Q
Proteins associated with Legionella-containing vesicle (LCV)
1)
2)
3)
4)
5)
6)
A

1) Rab1
2) Arf1
3) Sec22b
4) Calnexin
5) Sec61
Calnexin and Sec61 are ER proteins

34
Q

What is Arf1?

A

A GTPase

Involved in vesicle trafficking

35
Q

Type IV/Dot/Icm system

A

Pore-forming system

Delivers effector proteins through pores in host cell membrane

36
Q

Number of proteins involved in Dot/Icm

A

Over 300

1/3 of Leigonella genome dedicated to invasion

37
Q

Which bacterium expresses RomA?

A

Legionella

38
Q

Important protein expressed by Legionella, involved in epigenetic remodelling

A

RomA

39
Q

RomA function

A

1) Contains SET domain
2) SET domain is in eukaryotic histone lysine methyltransferases
3) RomA has a nuclear localisation sequence, enters the nucleus
4) Trimethylates histone H3K14, leading to transcriptional repression of TLR, cytokine genes

40
Q

Unusual feature of RomA

A

Trimethylates H3K14, which is never methylated normally

Normally H3K14 is acetylated

41
Q

Genes repressed by RomA

A

Cytokine, TLR genes.