Regulatory interplay between proton motive force, ADP, phosphate, and subunit epsilon in bacterial ATP synthase.
ATP synthase couples transmembrane proton transport, driven by the proton motive force (pmf), to the synthesis of ATP from ADP and inorganic phosphate (P(i)). In certain bacteria, the reaction is reversed and the enzyme generates pmf, working as a proton-pumping ATPase. The ATPase activity of bacterial enzymes is prone to inhibition by both ADP and the C-terminal domain of subunit epsilon. We studied the effects of ADP, P(i), pmf, and the C-terminal domain of subunit epsilon on the ATPase activity of thermophilic Bacillus PS3 and Escherichia coli ATP synthases. We found that pmf relieved ADP inhibition during steady-state ATP hydrolysis, but only in the presence of P(i). The C-terminal domain of subunit epsilon in the Bacillus PS3 enzyme enhanced ADP inhibition by counteracting the effects of pmf. It appears that these features allow the enzyme to promptly respond to changes in the ATP:ADP ratio and in pmf levels in order to avoid potentially wasteful ATP hydrolysis in vivo.
Feniouk
Boris A
BA
ATP System Project, Exploratory Research for Advanced Technology, Japan Science and Technology Corporation, Midori-ku, Yokohama 226-0026, Japan.
Suzuki
Toshiharu
T
Yoshida
Masasuke
M
D000244:Adenosine Diphosphate / Q000737:chemistry*; D000251:Adenosine Triphosphatases / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008081:Liposomes / Q000737:chemistry; D025261:Mitochondrial Proton-Translocating ATPases / Q000737:chemistry*; D008954:Models, Biological; D008958:Models, Molecular; D008968:Molecular Conformation; D010710:Phosphates / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011510:Proteolipids / Q000737:chemistry; D011522:Protons
D008081:Liposomes; D010710:Phosphates; D011510:Proteolipids; D011522:Protons; C020485:proteoliposomes; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases