proton-transporting two-sector ATPase complex

Definition

Target type: cellularcomponent

A large protein complex that catalyzes the synthesis or hydrolysis of ATP by a rotational mechanism, coupled to the transport of protons across a membrane. The complex comprises a membrane sector (F0, V0, or A0) that carries out proton transport and a cytoplasmic compartment sector (F1, V1, or A1) that catalyzes ATP synthesis or hydrolysis. Two major types have been characterized: V-type ATPases couple ATP hydrolysis to the transport of protons across a concentration gradient, whereas F-type ATPases, also known as ATP synthases, normally run in the reverse direction to utilize energy from a proton concentration or electrochemical gradient to synthesize ATP. A third type, A-type ATPases have been found in archaea, and are closely related to eukaryotic V-type ATPases but are reversible. [GOC:mah, ISBN:0716743663, PMID:16691483]

The proton-transporting two-sector ATPase complex, also known as F-type ATPase, is a highly conserved enzyme responsible for ATP synthesis in most living organisms. It is a complex assembly of multiple protein subunits, organized into two distinct domains: F1 and F0. The F1 domain protrudes into the cytoplasm and is responsible for ATP synthesis, while the F0 domain is embedded in the membrane and facilitates proton transport across the membrane.

The F1 domain is composed of five different subunits: α, β, γ, δ, and ε. The α and β subunits form a hexameric ring structure, alternating in sequence. Three catalytic sites are located at the interface of the α and β subunits, where ATP is synthesized. The γ subunit acts as a central stalk, connecting the F1 domain to the F0 domain and serving as a rotor during ATP synthesis. The δ and ε subunits play regulatory roles.

The F0 domain, also known as the membrane domain, is composed of three subunits: a, b, and c. The c subunit is the most abundant subunit, forming a ring-like structure that spans the membrane. The c subunit is the proton channel responsible for proton translocation. The a subunit acts as a stator, holding the c ring stationary, while the b subunit functions as a linker between the a subunit and the F1 domain.

During ATP synthesis, protons flow through the c ring, driven by the electrochemical gradient across the membrane. This proton flow causes the c ring to rotate, which in turn rotates the γ subunit within the F1 domain. This rotation triggers conformational changes in the catalytic sites of the α and β subunits, leading to the synthesis of ATP from ADP and phosphate.

In summary, the proton-transporting two-sector ATPase complex is a complex molecular machine that harnesses the energy of proton gradients to synthesize ATP. Its complex architecture and intricate mechanisms are essential for cellular energy production and are vital for life.'
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Proteins (1)

Compounds (1)