Microbiology Quiz 7 Flashcards
(16 cards)
1
Q
The Sec Pathway
A
- Sec and Tat are on the inner membrane
- Transport protein to the periplasm or membrane
2
Q
SecB Pathway
A
- relatively narrow translocons
- Transport proteins from plasma to periplasm
- Unfolded protein
3
Q
SecA
A
- Guides proteins to the SecYEG channel
- Serves as the ATPase that provides the energy for protein translocation
4
Q
Sec/SRP Pathway
A
- Inserts proteins into the inner membrane
- Membrane-bound
- Co-translation mechanism of export to secrete proteins going to the inner membrane
- SRP binds target proteins as they emerge from the ribosome and recruits the docking protein FtsY
5
Q
Tat Pathway
A
- Secretes fully folded proteins into the periplasm
- TatB and TatC bind the signal peptide of Tat-secreted proteins then recruit TatA which forms the membrane-spanning channels
6
Q
Type 1 Secretion
A
- 3 part system
- Beta barrel, channel, ATPase
- bacterial cytoplasm to the extracellular space
7
Q
Type 2 Secretion
A
- Periplasm into the extracellular space
- requires more proteins
- secrete protein in periplasm
8
Q
Type 3 Secretion
A
- Inner membrane to host cell
- Secretes proteins directly to host cell
- typically encoded in a few operons which can be found in in large regions of DNA w/ lots of virulence in the bacterial chromosome or on plasmid
8
Q
Toxins associated with T2SS
A
- Type 2 secretion system
- Endocytosed into cell for function
- cholera toxin (V. cholerae)
- Exotoxin A of P. aeruginosa
9
Q
T3SS Structure
A
- base complex or basal body, needle, and the translocon
- Base spans the inner and outer membranes, forming a socket-like structure consisting of several rings with a center rod
- Needle extends through the secretin and into the extracellular space
- Translocon is specific protein at needle tip allowing it to insert and secrete
10
Q
Type 4 Secretion
A
- direct transfer from cytoplasm to cytoplasm
- inner membrane to host membrane
- Related to bacterial DNA conjugation systems (makes it unique)
- More like a needle
- causes complete remodeling of endosomes
- crosses endosomal membrane
11
Q
Type 5 Secretion System
A
- found in the outermost membrane
- autotransporter
- multi-domained single protein
-broad secretion system
12
Q
Type 6 Secretion System
A
- across both membranes into host cell
- can hide from immune system
- regulated from extracellular signals
13
Q
Chaperone/Usher Pathway
A
- Forms pili/fimbriae for host cell adhesion
- found in a number of human pathogens
- bacteria can have multiple copies of these pathways that allow for adhesion to different proteins
14
Q
Chaperon/Usher Assembly
A
- Hand over hand mechanism
- Beta barrel protein is usher
- Sec B (secrete unfolded proteins)
15
Q
Yersinia Pestis
A
- KIM 5+
- KIM 6+ (No type 3 secretion)
- KIM 5- (Type 3 secretion, NO PGM LOCUS)
- PGM locus is the virulence island (iron acquisition genes)
