Inhibition of F1-ATPase rotational catalysis by the carboxyl-terminal domain of the ? subunit.

ABSTRACT: Escherichia coli ATP synthase (F0F1) couples catalysis and proton transport through subunit rotation. The ? subunit, an endogenous inhibitor, lowers F1-ATPase activity by decreasing the rotation speed and extending the duration of the inhibited state (Sekiya, M., Hosokawa, H., Nakanishi-Matsui, M., Al-Shawi, M. K., Nakamoto, R. K., and Futai, M. (2010) Single molecule behavior of inhibited and active states of Escherichia coli ATP synthase F1 rotation. J. Biol. Chem. 285, 42058-42067). In this study, we constructed a series of ? subunits truncated successively from the carboxyl-terminal domain (helix 1/loop 2/helix 2) and examined their effects on rotational catalysis (ATPase activity, average rotation rate, and duration of inhibited state). As expected, the ? subunit lacking helix 2 caused about ½-fold reduced inhibition, and that without loop 2/helix 2 or helix 1/loop 2/helix 2 showed a further reduced effect. Substitution of ?Ser(108) in loop 2 and ?Tyr(114) in helix 2, which possibly interact with the ? and ? subunits, respectively, decreased the inhibitory effect. These results suggest that the carboxyl-terminal domain of the ? subunit plays a pivotal role in the inhibition of F1 rotation through interaction with other subunits.

SUBMITTER: Nakanishi-Matsui M 

PROVIDER: S-EPMC4215258 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature