-
Gram (-) bacteria transport solutes across....?
•Periplasm
•Cytoplasmic membrane
-
Gram (+) bacteria transport solutes across....?
Only a single membrane.
-
LamB Porin transports what types of molecules?
Large ones, 600-6000
-
FhuA channel is specific for what..?
Iron containing siderophores, ferrichrome.
-
Abundant molecules are transported across the cell membrane through..?
OMPF - (outer membrane protein F)
-
Vitamin B12 is transported through the cell membrane via...?
BtuB protein
-
Name 3 functions of the Cytoplasmic membrane:
- –Solute transport
- –Electron transport
- –Photosynthetic electron transport
- –Maintain electrochemical gradients
- –ATP synthesis
- –Lipid biosynthesis
- –Biosynthesis of cell wall
- –Protein secretion
- –Secretion and uptake of intracellular signals
- –Responses to environmental signals
-
Define Vmax in terms of solute uptake:
Is the maximum rate or transport and occurs when all transporters occupied
-
What happens when there is solute uptake in the absence of active transport..?
The cell does not approach a maximum, even at high solute concentrations.
-
Define primary transport and give an example:
Is a transport system driven by energy, producing metabolic event.
Example: Uptake of solutes driven by ATP
-
Define secondary transport and give an example:
Secondary transport systems are driven by electrochemical gradients
Example: Solute moves “down” electrochemical gradient (protons or sodium ions).
-
Define simple transport:
Transport driven by the energy in the proton motive force
-
Define group translocation:
Chemical modification of the transported substance driven by phosphoenolpyruvate.
-
Define the ABC transport system
Periplamic binding proteins are involved and energy comes from ATP.
-
Name the 3 cytoplasmic membrance transporters and what gradient they use:
- B: TRAP transporter; H+ gradient
- C: MFS transporter; electrochemical gradient
- D: Uniporter; gradient of the substrate
-
What type of transport is the phosphotransferase stystem (PTS)?
Group translocation
-
Name the 2 subunits of ABC transporters:
- 1) A “power plant” which
- is the namesake: ABC subunit
2) The membrane translocation channel (MTC)
-
Whats the additional subunit of the importing ABC transport system?
- Extracytoplasmic solute receptor (ESR)
- - determines the specificity of a transporter
-
Name the 2 transporters involved for arabinose..
- 1) AraE; MFS transporter
- 2) AraFGH; ABC transporter
- Both activated by CRP and AraC
-
What proteins to arabinose bind to?
AraC & AraF
-
Name 3 clusters for ligands of ESR..
–Cluster 1 – maltose, polysaccharides and phosphate
–Cluster 2 – hexose and pentose sugars
–Cluster 3 – polar amino acids
–Cluster 4 – aliphatic amino acids
–Cluster 5 – peptides and nickel
–Cluster 6 – inorganic polyanions
–Cluster 7 – organic polyanions
–Cluster 8 – iron complexes
-
Define TRAP transporter:
- "intermediate transporter"
- A large family of solute transporters that appear to be specific for the uptake of organic acids.
-
name the 3 proteins of TRAP transporters
- 1) ESR
- 2) MTC
- 30 Membrane subunit
-
Define Siderophores:
Low molecular weight compounds with high affinity for iron.
-
What are the energy transducing proteins in transport against a concentration gradient?
-
Name the type of porin for each listed:
FepA-
FhuA-
FecA-
- FepA- Ferric Enterobactin Porin
- FhuA- Ferrichrome Porin
- FecA- Ferric Citrate Porin
-
Name the two domains of Outer Membrane Receptors:
- N-terminal "cork"domain
- C-terminal β-barrel
-
What are the 4 proteins of Ferrichrome transport?
- FhuA - cork domain
- FhuB - MTC
- FhuC - ABC
- FhuD - ESR
-
Name 3 ways to identify a ligand..
- Mass Spectrometry
- Fluorescence spectroscopy
- X-ray crystallography
-
Define Carbon Catabolite Repression:
- inhibitory effect of a certain carbon source on gene
- expression and/or activity of enzymes for utilization of other carbon sources.
-
How is CCR mediated in gram (+) bacteria?
Through negative regulation of genes for alternative carbond sources when glucose is present
-
How is CCR mediated in gram (-) Bacteria?
Through prevention of positive regulation of genes for alternative carbon sources when glucose is present.
-
Define the glucose effect
Observation that growth on glucose lowers activity of certain enzymes in bacteria and yeast.
-
Define Diauxie:
Many species, when grown with “good” and “poor” carbon sources will use good source first, experience lag, then resume growth on poor source (different growth rate)
-
Define Inducer Exclusion
Direct inhibition of transporters for alternative carbon sources when good carbon source (e.g., glucose) is available
-
Define:
EIIA
EIIB
EIIC
EIID
- EIIA: Soluble domain
- EIIB: Soluble domain
- EIIC: Integral membrane domain responsible for transport and phosphorylation of CHO - EIICB is membrane bound
- EIID: Unique to mannose family
-
P states of each protein is determined by..?
- PTS transport activity
- PEP
-
P-EIIAglc ativates what?
Adenylate Cyclase (making cAMP)
-
Explain how inducer exclusion works in EIIAglc
EIIAglc binds to and inhibits many non PTS proteins
-
The transport of glucose and other sugars reduces...?
cAMP levels
-
What is required for activation of genes encoding catabolic enzymes and transport proteins for many carbon sources?
CRP-cAMP
-
Unphosphorylated EIIAglc directly binds:
- -Permeases (lactose)
- -ATP binding subunit of ABC transporter (maltose)
- -Enzyme catalyzing formation of inducer (glycerol kinase)
-
What happens in the lag stage in Diauxic growth?
During lag, genes encoding enzymes for use of second carbon source synthesized
-
Synthesis of EII is usually controlled by?
Cognate sugar
-
Transcriptional regulation of PTS genes are tied to the phosphorylation state of ...?
EIICBglc
-
Name the 3 gene encoding regulators of the EII operons..
-Specific repressor- Mlc
-Antiterminator- BglG
-Transcriptional activator
-
When glucose enters the cell, the Mlc regulator binds to EIICBglc.. What does this enable?
- Transcription
- (if glucose does not enter the cell, transciption does not occur)
-
In transcriptional regulation, what is required for expression of PTS and non-PTS transport genes?
CRP-cAMP
-
Low GC gram (+) bacteria do not synthesize...
cAMP or posess CRP
-
What is the master regulator of CCR?
HPr protein
-
HPr function depends on..
its phosphorylation state.
-
What are the two sites for phosphorylation in HPr?
- 1) PEP dependent phosphorylation at His-15
- 2) ATP dependent phosphorylation at Ser-46
-
If there is P at the Ser-46 site what does that do to the His-15 site?
- Lowers the rate of P
- vice versa
-
What are two ways activity of regulatory enzymes can be modified?
- 1) The enzyme binds one or more biochemical intermediates of the pathway
- 2) Covalent modification
-
|
|