Lecture 12 - Intra-vacuolar Survival

Question 1

How does phagosomal maturation occur?
1)
2)

Answer 1

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

Question 2

Surface marker of late phagosome

Answer 2

LAMP-1

Question 3

How do phagosomal surface markers select specific endosomes?

Answer 3

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

Question 4

V-ATPase

Answer 4

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

Question 5

Which stage of vacuolar development does Mycobacterium live in?

Answer 5

Early endosome

Question 6

Which stage of vacuolar development does Salmonella live in?

Answer 6

Late endosome

Question 7

Which bacterium halts phagosomal development at early phagosome?

Answer 7

Mycobacterium

Question 8

Which bacterium halts phagosomal development at late endosome?

Answer 8

Salmonella

Question 9

Which bacterium lives in late phagosome?

Answer 9

Coxiella

Question 10

What does Coxiella burnetii cause?

Answer 10

Q fever

Question 11

Causative agent of Q fever

Answer 11

Coxiella burnetii

Question 12

Surface markers for late endosome

Answer 12

LAMP1, LAMP2, cathepsin D

Question 13

What is cathepsin D?

Answer 13

A protease

Question 14

Environment that Coxiella burnetii needs to replicate

Answer 14

Acidic

Below pH 5

Question 15

Close relative of Legionella

Answer 15

Coxiella burnetii

Question 16

Close relative of Coxiella

Answer 16

Legionella

Question 17

Secretion system used by Coxiella and Legionella

Answer 17

Type IV secretion system (Dot/Igm)

Question 18

Endosome always associated with macropinocytosis

Answer 18

Recycling endosome

Question 19

Filament produced by Salmonella in a vacuole

Answer 19

Salmonella induced filament (Sif)

Question 20

Where is Salmonella induced filament expressed?

Answer 20

Salmonella containing vacuole

Question 21

Phagosomal components missing in SCV
1)
2)
3)

Answer 21

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

Question 22

Which bacterium resides in a spacious phagosome?

Answer 22

Salmonella

Question 23

Which bacterium expresses SifA?

Answer 23

Salmonella

Question 24

Protein expressed by Salmonella to induce Sif formation

Answer 24

SifA

Question 25

Targets of SifA

Answer 25

Rab7 | SKIP (mammalian kinesin binding protein)

Question 26

Kinesin

Answer 26

Protein involved in transporting vesicles along microtubules

Question 27

Movement of Salmonella-containig vesicle

Answer 27

From periphery down to near nucleus

Question 28

What encodes SifA?

Answer 28

SPI-2

Question 29

Which kind of pathogen is Legionella?

Answer 29

Facultative intracellular pathogen

Question 30

Human cell in which Legionella replicates

Answer 30

Alveolar macrophage

Question 31

How good is Legionella at avoiding human immune system?

Answer 31

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

Question 32

At which stage does Legionella halt phagosome formation?

Answer 32

Doesn't even interact with early endosome. Very, very early

Question 33

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

Answer 33

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

Question 34

What is Arf1?

Answer 34

A GTPase | Involved in vesicle trafficking

Question 35

Type IV/Dot/Icm system

Answer 35

Pore-forming system | Delivers effector proteins through pores in host cell membrane

Question 36

Number of proteins involved in Dot/Icm

Answer 36

Over 300 | 1/3 of Leigonella genome dedicated to invasion

Question 37

Which bacterium expresses RomA?

Answer 37

Legionella

Question 38

Important protein expressed by Legionella, involved in epigenetic remodelling

Answer 38

RomA

Question 39

RomA function

Answer 39

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

Question 40

Unusual feature of RomA

Answer 40

Trimethylates H3K14, which is never methylated normally | Normally H3K14 is acetylated

Question 41

Genes repressed by RomA

Answer 41

Cytokine, TLR genes.