Journal of Biological Physics

, Volume 34, Issue 1, pp 197–212

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

Original Paper

DOI: 10.1007/s10867-008-9114-z

Cite this article as:
García-Trejo, J.J. & Morales-Ríos, E. J Biol Phys (2008) 34: 197. doi:10.1007/s10867-008-9114-z

Abstract

The F1F0-adenosine triphosphate (ATP) synthase rotational motor synthesizes most of the ATP required for living from adenosine diphosphate, Pi, and a proton electrochemical gradient across energy-transducing membranes of bacteria, chloroplasts, and mitochondria. However, as a reversible nanomotor, it also hydrolyzes ATP during de-energized conditions in all energy-transducing systems. Thus, different subunits and mechanisms have emerged in nature to control the intrinsic rotation of the enzyme to favor the ATP synthase activity over its opposite and commonly wasteful ATPase turnover. Recent advances in the structural analysis of the bacterial and mitochondrial ATP synthases are summarized to review the distribution and mechanism of the subunits that are part of the central rotor and regulate its gyration. In eubacteria, the ε subunit works as a ratchet to favor the rotation of the central stalk in the ATP synthase direction by extending and contracting two α-helixes of its C-terminal side and also by binding ATP with low affinity in thermophilic bacteria. On the other hand, in bovine heart mitochondria, the so-called inhibitor protein (IF1) interferes with the intrinsic rotational mechanism of the central γ subunit and with the opening and closing of the catalytic β-subunits to inhibit its ATPase activity. Besides its inhibitory role, the IF1 protein also promotes the dimerization of the bovine and rat mitochondrial enzymes, albeit it is not essential for dimerization of the yeast F1F0 mitochondrial complex. High-resolution electron microscopy of the dimeric enzyme in its bovine and yeast forms shows a conical shape that is compatible with the role of the ATP synthase dimer in the formation of tubular the cristae membrane of mitochondria after further oligomerization. Dimerization of the mitochondrial ATP synthase diminishes the rotational drag of the central rotor that would decrease the coupling efficiency between rotation of the central stalk and ATP synthesis taking place at the F1 portion. In addition, F1F0 dimerization and its further oligomerization also increase the stability of the enzyme to natural or experimentally induced destabilizing conditions.

Keywords

F1F0 ATPaseF1F0 ATP synthaseIF1Inhibitor proteinEpsilonDimericRotationInterfaceCristaeRegulationF1 ATPase

Abbreviations

EF1, EF1F0

Escherichia coli F1 and F1F0 complexes

EM

electron microscopy

F1F0

the whole ATP synthase complex with its catalytic (F1) and proton channel (F0) parts

F1F0I

the whole ATP synthase containing its physiological inhibitor protein (IF1)

IF1

the intrinsic inhibitor protein of the mitochondrial ATP synthase

MF1, MF1F0

bovine heart mitochondrial F1 and F1F0 complexes, respectively

NMR

nuclear magnetic resonance spectroscopy

Copyright information

© Springer Science + Business Media B.V. 2008

Authors and Affiliations

  1. 1.Facultad de Química, Departamento de Biología, Lab. F-117Universidad Nacional Autónoma de MéxicoMéxico, D.F.México