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The regulator of the F 1 motor: inhibition of rotation of cyanobacterial F 1 ‐ATPase by the ε subunit
Author(s) -
Konno Hiroki,
MurakamiFuse Tomoe,
Fujii Fumihiko,
Koyama Fumie,
UeokaNakanishi Hanayo,
Pack ChanGi,
Kinjo Masataka,
Hisabori Toru
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601348
Subject(s) - biology , regulator , atpase , protein subunit , microbiology and biotechnology , enzyme , biochemistry , gene
The chloroplast‐type F 1 ATPase is the key enzyme of energy conversion in chloroplasts, and is regulated by the endogenous inhibitor ε, tightly bound ADP, the membrane potential and the redox state of the γ subunit. In order to understand the molecular mechanism of ε inhibition, we constructed an expression system for the α 3 β 3 γ subcomplex in thermophilic cyanobacteria allowing thorough investigation of ε inhibition. ε 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 γ subunit of chloroplast‐type F 1 ‐ATPase in ε inhibition was also determined. By single molecule rotation analysis, we succeeded in assigning the pausing angular position of γ in ε 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 ε subunit of chloroplast‐type ATP synthase plays an important regulator for the rotary motor enzyme, thus preventing wasteful ATP hydrolysis.