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J Biol Chem. 2009 Aug 14;284(33):22401-10. doi: 10.1074/jbc.M109.009019. Epub 2009 Jun 5.

Temperature dependence of single molecule rotation of the Escherichia coli ATP synthase F1 sector reveals the importance of gamma-beta subunit interactions in the catalytic dwell.

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1
Department of Biochemistry, Faculty of Pharmaceutical Sciences, and Futai Special Laboratory, Iwate Medical University, Yahaba, Iwate 028-3694, Japan.

Abstract

The temperature-dependent rotation of F1-ATPase gamma subunit was observed in V(max) conditions at low viscous drag using a 60-nm gold bead (Nakanishi-Matsui, M., Kashiwagi, S., Hosokawa, H., Cipriano, D. J., Dunn, S. D., Wada, Y., and Futai, M. (2006) J. Biol. Chem. 281, 4126-4131). The Arrhenius slopes of the speed of the individual 120 degrees steps and reciprocal of the pause length between rotation steps were very similar, indicating a flat energy pathway followed by the rotationally coupled catalytic cycle. In contrast, the Arrhenius slope of the reciprocal pause length of the gammaM23K mutant F1 was significantly increased, whereas that of the rotation rate was similar to wild type. The effects of the rotor gammaM23K substitution and the counteracting effects of betaE381D mutation in the interacting stator subunits demonstrate that the rotor-stator interactions play critical roles in the utilization of stored elastic energy. The gammaM23K enzyme must overcome an abrupt activation energy barrier, forcing it onto a less favored pathway that results in uncoupling catalysis from rotation.

PMID:
19502237
PMCID:
PMC2755962
DOI:
10.1074/jbc.M109.009019
[Indexed for MEDLINE]
Free PMC Article
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