Portal de Periódicos da CAPES

Thermophilic ATP synthase has a decamer c -ring: Indication of noninteger 10:3 H + /ATP ratio and permissive elastic coupling

2004; National Academy of Sciences; Volume: 101; Issue: 33 Linguagem: Inglês

10.1073/pnas.0403545101

1091-6490

Noriyo Mitome, Toshiharu Suzuki, Shigehiko Hayashi, Masasuke Yoshida,

Hybrid Renewable Energy Systems

In a rotary motor F o F 1 -ATP synthase that couples H + transport with ATP synthesis/hydrolysis, it is thought that an F o c subunit oligomer ring ( c -ring) in the membrane rotates as protons pass through F o and a 120° rotation produces one ATP at F 1 . Despite several structural studies, the copy number of F o c subunits in the c -ring has not been determined for any functional F o F 1 . Here, we have generated and isolated thermophilic Bacillus F o F 1 , each containing genetically fused 2-mer–14-mer c ( c 2 – c 14 ). Among them, F o F 1 containing c 2 , c 5 , or c 10 showed ATP-synthesis and other activities. When F 1 was removed, F o containing c 10 worked as an H + channel but F o s containing c 9 , c 11 or c 12 did not. Thus, the c -ring of functional F o F 1 of this organism is a decamer. The inevitable consequence of this finding is noninteger ratios of rotation step sizes of F 1 /F o (120°/36°) and of H + /ATP (10:3). This step-mismatch necessitates elastic twisting of the rotor shaft (and/or the side stalk) during rotation and permissive coupling between unit rotations by H + transport at F o and elementary events in catalysis at F 1 .