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Bacteriology > Lizzie > Flashcards

Lizzie Flashcards

1
Q

Listeria invasin InIA mediates high affinity interaction between bacteria and…

A

cell-cell adhesion protein E-cadherin (found on epithelial cell surface - mediate formation of Ca2+ dependent intercellular junctions

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2
Q

InB

A

binds hepatocyte growth factor receptor met which is expressed on all cell types –> internalization

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3
Q

T/F: Zipper and trigger mechanisms of invasion utilise same eukaryotic cell processes

A

FALSE:
Zipper - receptor mediated endocytosis
Trigger/ruffle: macropinocytosis

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4
Q

T/F: Shigella exploits host cell GTPases for invasion

A

TRUE:
Shigella activates host Rho family of GTPases to induce Arp2/3 and N-WASP dependent actin polymerization and membrane ruffling

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5
Q

T/F: Listeria and Shigella both utilise ARP2/3 AND N-WASP to induce actin filament formation which supports actin based motility

A

FALSE:
Shigella: N-wasp and arp2/3
Listeria: VASP and ARP2/3

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6
Q

IcsA Shigella protein

A

Required for actin based motility
Expressed at one pole of bacterium
Autotransporter proten
Binds directly to N-WASP via a glycine rich repeat region to recruit actin

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7
Q

Avoid destruction in phagosome by: (4)

A
  1. escaping into cytoplasm
  2. arresting development of phagosome to avoid identification
  3. remodelling phagosome by interacting with factors from ER
  4. adapting to survive in lysosome
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8
Q

T/F:Salmonella has 2 T3SS- one for invasion by ruffling and one for intracellular survival

A

TRUE:

2 T3SS and 2 sets of effector proteins

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9
Q

T/F: Legionella replicates in a vacuole that has characteristics of late endosomes

A

FALSE:

Does not interact with endocytic pathway, interacts with EXOCYTIC pathway - ER-exit vesicles

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10
Q

Transport across GN bacterial inner membrane by Sec translocase:

A

is assisted by SecB chaperone

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11
Q

T2SS

A

Protein for export carries an N-terminal signal peptide, which is cleaved by a specific signal peptidase
There is a periplasmic intermediate
Sec Dependent

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12
Q

T/F: T1SS are sec-dependent and utilise periplasmic intermediate

A

FALSE: T1 secrete proteins in one step

Sec independent and no periplasmic intermediate

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13
Q

DOT/ICM SS in legionella:

A

Translocates ~300 effector proteins
Forms an apparatus that spans inner and outer membrane of bacterium
=T4SS
close homologue to Coxiella

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14
Q

T6SS

A

Comprises components that are similar to bacteriophage proteins and type 4SS proteins

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15
Q

Advantages of invasion

A 
No competition
Inaccessible to complement and antibodies
Do not need to adhere 
Ready access to nutrients
May require host cell environment
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16
Q

Cytosolic niche

A

e. g. SHIGELLA AND LISTERIA
1. invade cells
2. escape vacuole and proliferate
3. recruit host cell cytoskeletal proteins
4. induce actin polymerization
5. formation of actin tails propels bacteria into adjacent cells

17
Q

cytosolic niche shigella

A
  1. invade through ruffling using T3SS AND IpA proteins

IcsA: formation of actin tail =polar, glycine rich repeat region

18
Q

CYTOSOLIC NICHE: listeria

A
  1. invade using zipper

ActA: expressed at pole, binds VASP and Arp2/3 for actin polymerization

19
Q

Oxygen dependent resipiratory burst

A

NADPH oxidase
O2-
H2O2
OCl- (reactive oxygen species)

20
Q

Oxygen independent

A 
low pH (lysosome)
proteolytic enzymes
lysosyme
lactoferrin
membrane damaging proteins
21
Q

Intralysosomal niche

A

e.g. coxiella
Grows optimally at pH <5
Dot Icm SS
vacuole contains markers for late endosomal lysosomal compartments

22
Q

Intravacuolar niche (delayed maturation)

A

e.g. Salmonella, Legionella

23
Q

Salmonella intravacuolar niche

A

Prevents phagolysosome fusion
SPI1: cytoskeletal rearrangements, diarrhoea, inflammation, INVASION
SPI2: INTRACELLULAR SURVIVAL AND REPLICATION, modification of vacuole trafficking, inhibition of respiratory burst (prevents NADPH assembly)

SifA: Induces Sif formation - maintains SCV integrity

24
Q

Legionella: intravacuolar niche

A

Facultative intracellular pathogen
Replicates in alveolar macrophage, amoebae=natural host
Phagosomes fail to acidify and fuse with lysosomes –> ER-like organelle

25
Q

General Secretory system (sec)

A

Common to GP and GN
Leader sequence (20aa) binds to SecB chaperone
Exports UNFOLDED proteins

SecB: tetramer, keeps proteins unfolded and delivers to SecA

SecA: Dimer, ATPase for energy, binds SecYEG which forms protein-conducting channel

26
Q

TAT PATHWAY = TWIN ARGININE TRANSPORT SYSTEM

A

GP AND GN

FOLDED proteins

27
Q

Autotransporters/T5SS

A

Protein deliver to periplasm via Sec
Sec system
B domain inserts into outer membrane and forms a pore structure
BAM complex assembles/inserts B-barrel in outer membrane

28
Q

TWO PARTNER SECRETION SYSTEM: SINGLE ACCESSORY PATHWAY

A

Similar to autotransporter + 1 additional protein

Secretes large virulence proteins

29
Q

Chaperone Usher pathway

A

Sec dependent
Transport pili
Chaperones FimC prevent pilin subunits from folding into final configuration
Usher: export pilin

30
Q

T2SS

A

SEC dependent
Related to type 4 pili
Outer membrane pore made up of GspD

31
Q

T1SS

A

Secretion of toxins, proteases, lipases
Sec independent
Secreted proteins bind ABC transporter protein via C-terminal signal sequence with glycine rich repeat
Signal sequence not cleaved

32
Q

T3SS

A

GN pathogens: e.g. Salmonella/shigella - invasion, EPEC-colonization
Sec independent
Directly secrete toxins
Contact dependent
Injectosome: molecular syringe, ATP dependent

33
Q

T4SS

A

Related to Bacterial conjugation systems
12 proteins form tunnel
Transfers Ti plasmid and proteins from bacterium to plant cell –> tumor in plants
e.g. legionella

34
Q

T6SS

A

Share structural features with bacteriophage cell puncturing protein
Prototype = pseudomonas
Similar to Dot/Icm

35
Q

T7SS

A

Some GP
Transports proteins through thick mycobacterial cell wall
e.g. mycobacterium tuberculosis

Bacteriology (8 decks)

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