Gene Regulation Following Envelope Stress Flashcards
Is E. coli Gram +ve or -ve?
Gram -ve
How many membranes in E. coli envelope?
2
What are some of the roles of the E. coli envelope?
Shape, metabolism, transport of molecules, protection, motility
What is the E. coli envelope structure?
Lipopolysaccharide
Phospholipid
Peptidoglycan Cell Wall
Phospholipid
What are some of the E. coli cell envelope proteins?
Transporter, Porin, Lipoprotein, Protease, Chaperone
What are some of the systems that respond to E. coli cell stress?
sigmaE system - OM defects
CpxAR - IM and periplasm defects
Phage shock protein - IM permeability
PhoPQ - LPS defects
What does the sigmaE system do?
Maintains homeostasis of the outer membrane by monitoring fidelity of outer membrane protein biogenesis
Steps in sigmaE proteolytic cascade
Environmental stress causes misfolded OMPs and LPS
Periplasmic LPS binds with RseB removing it from RseA
YxF in unfolded porin interacts with DegS
DegS degrades RseA in periplasmic space
RseP degreades RseA in inner membrane
ClpXP degrades rest of RseA releasing sigmaE
What does sigmaE do?
Activate transcription
Increase OMP biogenesis capacity
What do small regulatory sRNAs do in the stress response?
Fast adjustment to conditions
Act at post-transcriptional level
Need RNA chaperone - Hfq
How can sRNAs repress expression?
Bind to ribosome binding site
Recruit RNase
How can sRNAa activate expression?
Free the ribosome binding site
Block RNase from degrading
What can sRNAs do to regulators?
Sequester +ve regulators
Sequester -ve regulators
