title: The regulator of the F1 motor: inhibition of rotation of cyanobacterial F1-ATPase by the epsilon subunit.
abstract: The chloroplast-type F(1) ATPase is the key enzyme of energy conversion in chloroplasts, and is regulated by the endogenous inhibitor epsilon, tightly bound ADP, the membrane potential and the redox state of the gamma subunit. In order to understand the molecular mechanism of epsilon inhibition, we constructed an expression system for the alpha(3)beta(3)gamma subcomplex in thermophilic cyanobacteria allowing thorough investigation of epsilon inhibition. epsilon Inhibition was found to be ATP-independent, and different to that observed for bacterial F(1)-ATPase. The role of the additional region on the gamma subunit of chloroplast-type F(1)-ATPase in epsilon inhibition was also determined. By single molecule rotation analysis, we succeeded in assigning the pausing angular position of gamma in epsilon inhibition, which was found to be identical to that observed for ATP hydrolysis, product release and ADP inhibition, but distinctly different from the waiting position for ATP binding. These results suggest that the epsilon subunit of chloroplast-type ATP synthase plays an important regulator for the rotary motor enzyme, thus preventing wasteful ATP hydrolysis.
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta, Yokohama, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Konno
authors.forename: Tomoe
authors.initials: T
authors.lastname: Murakami-Fuse
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Fujii
authors.forename: Fumie
authors.initials: F
authors.lastname: Koyama
authors.forename: Hanayo
authors.initials: H
authors.lastname: Ueoka-Nakanishi
authors.forename: Chan-Gi
authors.initials: CG
authors.lastname: Pack
authors.forename: Masataka
authors.initials: M
authors.lastname: Kinjo
authors.forename: Toru
authors.initials: T
authors.lastname: Hisabori
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000458:Cyanobacteria / Q000201:enzymology*; D004123:Dimethylamines / Q000494:pharmacology; D006868:Hydrolysis / Q000187:drug effects; D020409:Molecular Motor Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D012399:Rotation
chemical_list: D004123:Dimethylamines; D020409:Molecular Motor Proteins; D050505:Mutant Proteins; D021122:Protein Subunits; C014518:dodecyldimethylamine oxide; D000255:Adenosine Triphosphate; C444660:gamma subunit, F(1) ATPase; D006180:Proton-Translocating ATPases