F1F0komplex

F1F0komplex, also known as the F1F0-ATP synthase, is a highly conserved enzyme complex that converts the energy stored in a proton motive force across a membrane into chemical energy in the form of ATP. It is essential for cellular energy production in bacteria, mitochondria, and chloroplasts, and can operate in reverse to hydrolyze ATP to pump protons when needed.

The enzyme consists of two linked but distinct rotary sectors. The F0 portion is embedded in the membrane and forms the proton channel and rotor, including a subunit complex that creates a c-ring. The F1 portion protrudes into the cytoplasm or mitochondrial matrix and contains the catalytic α3β3 hexamer around a central γ subunit; this headpiece carries the active sites for ATP synthesis. The two sectors are connected via a stator to prevent total dissociation, allowing the rotor to turn while the catalytic head remains stationary relative to the surrounding medium.

Functioning as a rotary motor, proton translocation through F0 drives rotation of the c-ring and the attached γ subunit. This mechanical energy induces conformational changes in the αβ catalytic sites, catalyzing the formation of ATP from ADP and inorganic phosphate. The complex can also operate in reverse, using cellular ATP to pump protons across the membrane, contributing to membrane potential under certain conditions.

Stoichiometry and efficiency vary by organism due to differences in the c-ring composition. A full rotation typically produces three ATP, and the number of protons required per rotation equals the number of c-subunits in the ring, making protons per ATP organism-dependent.

Disruption of F1F0komplex function affects cellular energy balance and is linked to mitochondrial diseases. It is a frequent subject of structural and biophysical studies, with abundant data from X-ray crystallography and cryo-electron microscopy highlighting its conserved architecture and rotary mechanism.