In: Biology
Describe in mechanistic detail at the level of protein subunits and specific sites in them how the F0 rotor is driven. What is the role of the stator argine?
Please be detailed in response.
how the F0 rotor is driven:-
F-ATPases (also known as ATP synthases, F1F0-ATPase, or
H(+)-transporting two-sector ATPase) are composed of two linked
complexes: the F1 ATPase complex is the catalytic core and is
composed of 5 subunits (alpha, beta, gamma, delta, epsilon), while
the F0 ATPase complex is the membrane-embedded proton channel that
is composed of at least 3 subunits (A-C), with additional subunits
in mitochondria. Both the F1 and F0 complexes are rotary motors
that are coupled back-to-back. In the F1 complex, the central gamma
subunit forms the rotor inside the cylinder made of the
alpha(3)beta(3) subunits, while in the F0 complex, the ring-shaped
C subunits forms the rotor. The two rotors rotate in opposite
directions, but the F0 rotor is usually stronger, using the force
from the proton gradient to push the F1 rotor in reverse in order
to drive ATP synthesis [1]. These ATPases can also work in reverse
in bacteria, hydrolysing ATP to create a proton gradient.
This superfamily represents the up-and-down bundle of four
transmembrane helices structure found in the F0 complex subunit A.
This subunit is a key component of the proton channel, and may play
a direct role in the translocation of protons across the membrane.
Catalysis in the F1 complex depends upon the rotation of the
central stalk and F0 c-ring, which in turn is driven by the flux of
protons through the membrane via the interface between the F0
c-ring and subunit A. The peripheral stalk links subunit A to the
external surface of the F1 domain, and is thought to act as a
stator to counter the tendency of subunit A and the F1
alpha(3)beta(3) catalytic portion to rotate with the central rotary
element .
What is the role of the stator argine:-
The negative charge of the binding site is compensated by the stator arginine.