E. coli Stress Response Flashcards
Roles of EC fell envelope?
Signal Transduction ~
Energy, Metabolism, Respiration
Defence, Protection, Resistance
Elongation, Shape, Motility
Virulence, Attachment, Biofilm
Transport, Selection, Chemotaxis,
Separation
Outline the basic EC envelope structure (draw)
(OM:)
Lipopolysaccharide - LPS
Phospholipid - PL
(PP:)
Peptidoglycan Cell Wall - PG
(IM:)
Phospholipid - PL
Phospholipid - PL
Where are active transporters found? What do they do?
They transport OUT AND IN
They are across OM, IM and spanning between them
What are porins? Where are they found?
They are passive transporters
(hphilic molecules - permeable)
They are in OM
Where are Lipoproteins? What do they do?
They are anchored between PG and PL layers
They do lots of stuff
Sig Trans, nutrients, transport, etc
Where are proteases? What do they do?
Eat inactive proteins
They are in PP and IM
Where are chaperones? What do they do?
They fix wrongly-folded proteins
They are in PP
Where is the highest density of proteins in E. coli?
The periplasm (PP)
What kinds of stress can trigger response in bacteria?
- Environmental
- Membrane permeability
- Problems with proteins
What does the sigma E response help with?
OM defects
What does the CpxAR response help with?
IM + PP defects
What does the Phage Shock Protein (Psp) response help with?
IM permeability
What does the BaeSR response help with?
Pump out damaging agents
efflux pumps
- What does the PhoPQ response help with? (Non-Env system)
LPS defects
Activated My MicA!
What does the Outer Membrane Vesicle response help with?
Why is it different from ever response systems?
Increases hydrophobicity
Different because it does not involve activation of genes
- What IS sigma E?
An alternate Sigma Factor which controls extracytoplasmic stress response.
It enables RNA pol to increase TS of certain genes
Previously thought to only be essential at high temperatures, but it’s ESSENTIAL at all
- What is the role of the Sigma E system?
Maintain HOMEOSTASIS of outer membrane
By monitoring OM protein BIOGENESIS
What are the actors in the Sigma E system?
RseA - antisigma
RseB - negative reg
DegS - protease (PP domain)
RseP - protease (IM domain)
Clp XP - protease (Cytoplasm)
What physical stresses will active the Sigma E system?
Heat
Ethanol
Growth phase
What do the stresses to do the OM Which activates the Sigma E system?
Misfold OMPs and LPS
Proteins end up in cytoplasm
YxF domain of PORIN is exposed
What do the Perplasmic LPS and Porin YxF do to activate the Sigma E system?
LPS takes away RseB -
RseA is vulnerable
YxF activates DegS -
DegS noms RseA
~ PP domain only (1/3) ~
How are the domains of RseA destroyed?
Once PP region is vulnerable, activate DegA noms it (1/3)
RseP noms IM domain (2/3)
CP domain now free in CP, nommed by ClpXP, releasing Sigma E (3/3)
What is the PRO-TS of Sigma E?
Activate >100 Genes to REGULATE OMP Synthesis
Increase Chaperones and Proteases
(get rid of stress)
Increase OMP biogenesis
(New, Good proteins)
Increase TPort machinery
(Get rid of broken proteins)
Other TS regulators
(communication)
How does Sigma E get Positive and Negative feedback?
Activates its OWN regulon:
rpoE (encodes Sigma E)
rseABC (captuses Sigma E)
