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Chemo-mechanical coupling in F(1)-ATPase revealed by catalytic site occupancy during catalysis.

ABSTRACT: F(1)-ATPase is a rotary molecular motor in which the central gamma subunit rotates inside a cylinder made of alpha(3)beta(3) subunits. To clarify how ATP hydrolysis in three catalytic sites cooperate to drive rotation, we measured the site occupancy, the number of catalytic sites occupied by a nucleotide, while assessing the hydrolysis activity under identical conditions. The results show hitherto unsettled timings of ADP and phosphate releases: starting with ATP binding to a catalytic site at an ATP-waiting gamma angle defined as 0 degrees , phosphate is released at approximately 200 degrees , and ADP is released during quick rotation between 240 degrees and 320 degrees that is initiated by binding of a third ATP. The site occupancy remains two except for a brief moment after the ATP binding, but the third vacant site can bind a medium nucleotide weakly.

SUBMITTER: Shimo-Kon R

PROVIDER: S-EPMC2849061 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

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Chemo-mechanical coupling in F(1)-ATPase revealed by catalytic site occupancy during catalysis.

Shimo-Kon Rieko R Muneyuki Eiro E Sakai Hiroshi H Adachi Kengo K Yoshida Masasuke M Kinosita Kazuhiko K

Biophysical journal 20100401 7

F(1)-ATPase is a rotary molecular motor in which the central gamma subunit rotates inside a cylinder made of alpha(3)beta(3) subunits. To clarify how ATP hydrolysis in three catalytic sites cooperate to drive rotation, we measured the site occupancy, the number of catalytic sites occupied by a nucleotide, while assessing the hydrolysis activity under identical conditions. The results show hitherto unsettled timings of ADP and phosphate releases: starting with ATP binding to a catalytic site at a ...[more]

PMID: 20371322

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