Structure - Bacterial Movement Flashcards
What are the three structures of
Basal Body
Hook
Filament
What is the function of the Basal Body?
Drives rotary motion of the flagella through the MS-ring
MS-Ring
A transmembrane complex acting as the core of the flagellar motor and template for flagellar assembly.
What is the function of MS-Ring?
Forms a membrane pore to allow ionic flow for rotary motion generation.
What is the function of FliG?
Interacts with flagellar motor proteins to regulat direction of flagellar motion.
What are the three rings of he flagellar?
MS-Ring
L-Ring
P-Ring
What is the Hook composed of?
FlgE protein
What is the structure of the FlgE protein?
Banana-like conformation with an NTD anchoring to the basal body and CTD binding hook and filament.
What is FlgE important for?
Mobility regulation, with length and shape able to be controlled
What is the filament composed on?
Flagellin proteins in a helical arrangement
What is the function of the filament?
Propelling bacteria throguh mediums.
What is the 3D structure of the flagellin?
11 protofilaments winding around each other, each composed of several flagelling
What is the primary motor ring?
C-Ring composed of FliG protein
How is movement driven in the C-Ring?
FliM and FliN rotate when ions flow through the motor.
What is the importance of the Proton Motive Force in rotation?
ETC pump ions creating an electrocemical gradient either side of the membrane, where the motor reverts this flow to generate force rotating the C-RINg
What does the Proton Motive Force do for torque generation?
Creates and electrical potential and pH higher outside the membrane driving protons back into the cell.
What drives proton flow across the membrane?
Stator complex of MotA and MotB with interaction with C-ring charged residues causing either CW or CCW
FliM
This stabilises charged residues in FliG to organise rotation
FliN
This stabilises FliM and FliG interactions forming a hexameric ring in the centre of the C-Ring
How is torque generated by the stator?
Release of stored energy by conformational changes or generation of electric field interaction with stator complex.
Run
Linear motion by chemotaxis reocngition of environmental attractants or repllants
Tumbles
Rapid switches in directions of rotation changing thus orientiation and direction of movement
Chemoreceptors
These detect concentration gradients in the environment and through signally pathways relay this to the motor.
CheY
This is an enzyme catalysing phosphoryl group transfer from phosphohistidine in CheA to its own aspartate residues inducing CC allowing CheA binding to flagellar motor.
What happens to CheZ in presence of repellants?
CheZ increases in concentration removing the phosphoryl group from CheY resulting in tumbles.
What happens when chemoreceptor binds attractants?
CC triggered and CheA autophosphorylates a hisitinde residues transferring phosphoryl to aspartate on CheY allowing its interaction with flagellar.
Polar Flagellation
Flagella attaches at one/both ends of the cell.
Lophotrichous
Having multiple flagella at the same point
Peritrichous
Flagella inserts at many locations around cell surface
Amphitrichous
Flagella is found both poles of the cell.
Chemotaxis
The ability of bacteria to move toward a location in response to electrochemical graidents.
What does both CCW and CW cause?
CCW causes tumbling and CW causes Run
How fast can the flagellar rotate?
300 revs per second and 60 cell lengths per second.
