F0F1 ATPase - aka ATP Synthase
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I. Introduction
The Protein Data Bank describes ATP
Synthase as consisting of two interconnecting rotary motors.
- The F0 membrane domain acts as an electrical rotary
motor powered by the flow of protons across the membrane which causes
rotary motion in the membrane c subunits. As Einstein
described the nature of relative motion, this rotation is expressed not
as the rotation of the membrane c subunits with respect to themselves,
but of a rotary "axle" protein complex connected to the static c helices
- The F1 domain in the matrix acts as a chemical rotary motor powered by ATP
hydrolysis. Likewise this domain is connected to the axle rotor.
The motor is run backward during the collapse of the proton gradient to synthesize ATP.
- Both rotary motors are connected by a "stator" which links their
rotations so if one domain rotates, the other does as well.
For more information see
Biochemistry Online: Chapter
8C-10: Proton Gradient Collapse and ATP synthesis - Structure
II. General Structure
A. F1 ATPase Matrix Chemical Motor
The matrix domain core consist of a repeating (alph-beta)3
structure , .
highlight F0 alpha subunits - red cartoon
highlight F0 beta subunits - orange cartoon
B. Rotor/Axle connecting F0 and F1
highlight Rotor gamma subunit - purple cartoon
highlight Rotor delta subunit connecting gamma and membrane domain - magenta cartoon
highlight Rotor epsilon subunit which runs across parallel to the membrane - medium orchid cartoon
C. F0 membrane Electric Motor
Proton transfer occurs across this domain which consists of 12 identical c
subunits each with an Asp 61 involved in rotating interactions with an Arg 210
on subunit A (missing from this model).
highlight membrane domain with c subunits - yellow cartoon
The isolated membrane F0 domain (pdb id: 1C17) from E. Coli in complex with the A subunit. The Asps 61s are shown in sticks in F0. The A chain (fuchsia, not shown in the links above) is shown with Arg 271 interacting with Asp 61s on the c chains. This pdb files shows the full c helices not found in the complete model shown in the links above and below)
rotate to see top down view of membrane plane to better see the interaction between the A chain Arg 271 and the adjacent C chain Asp 61s
path for H+ proton flow from Arg 271 of the A chain through adjacent transmembreane c helices in the F0 membrane domain. The A chain amino acids include Gln 252, Asn 214, Asn 148, Asp 119, His 245, Glu 219, Ser 144 and Asn 238.
D. Stator and peripheral subunits affecting activity
Oligomycin A binds between the a and c subunits in the F0 domain and inhibits
proton transport. Inhibition requires a distal OSCP (Oligomycin-Sensitivity Conferring Protein which is analogous to the bacterial delta subunit), a stalk protein subunit distal to Fo which couples Fo and F1.
highlight OSCP - lime cartoon
highlight peripheral stalk and stator - green cartoon
Note the additional protein changes involved in the complex.