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Engineering rotor ring stoichiometries in the ATP synthase.

ABSTRACT: ATP synthase membrane rotors consist of a ring of c-subunits whose stoichiometry is constant for a given species but variable across different ones. We investigated the importance of c/c-subunit contacts by site-directed mutagenesis of a conserved stretch of glycines (GxGxGxGxG) in a bacterial c(11) ring. Structural and biochemical studies show a direct, specific influence on the c-subunit stoichiometry, revealing c(<11), c(12), c(13), c(14), and c(>14) rings. Molecular dynamics simulations rationalize this effect in terms of the energetics and geometry of the c-subunit interfaces. Quantitative data from a spectroscopic interaction study demonstrate that the complex assembly is independent of the c-ring size. Real-time ATP synthesis experiments in proteoliposomes show the mutant enzyme, harboring the larger c(12) instead of c(11), is functional at lower ion motive force. The high degree of compliance in the architecture of the ATP synthase rotor offers a rationale for the natural diversity of c-ring stoichiometries, which likely reflect adaptations to specific bioenergetic demands. These results provide the basis for bioengineering ATP synthases with customized ion-to-ATP ratios, by sequence modifications.

SUBMITTER: Pogoryelov D

PROVIDER: S-EPMC3382517 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Engineering rotor ring stoichiometries in the ATP synthase.

Pogoryelov Denys D Klyszejko Adriana L AL Krasnoselska Ganna O GO Heller Eva-Maria EM Leone Vanessa V Langer Julian D JD Vonck Janet J Müller Daniel J DJ Faraldo-Gómez José D JD Meier Thomas T

Proceedings of the National Academy of Sciences of the United States of America 20120524 25

ATP synthase membrane rotors consist of a ring of c-subunits whose stoichiometry is constant for a given species but variable across different ones. We investigated the importance of c/c-subunit contacts by site-directed mutagenesis of a conserved stretch of glycines (GxGxGxGxG) in a bacterial c(11) ring. Structural and biochemical studies show a direct, specific influence on the c-subunit stoichiometry, revealing c(<11), c(12), c(13), c(14), and c(>14) rings. Molecular dynamics simulations rati ...[more]

PMID: 22628564

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Project description:The proton-driven ATP synthase (FOF1) is comprised of two rotary, stepping motors (FO and F1) coupled by an elastic power transmission. The elastic compliance resides in the rotor module that includes the membrane-embedded FO c-ring. Proton transport by FO is firmly coupled to the rotation of the c-ring relative to other FO subunits (ab2). It drives ATP synthesis. We used a computational method to investigate the contribution of the c-ring to the total elastic compliance. We performed principal component analysis of conformational ensembles built using distance constraints from the bovine mitochondrial c-ring x-ray structure. Angular rotary twist, the dominant ring motion, was estimated to show that the c-ring accounted in part for the measured compliance. Ring rotation was entrained to rotation of the external helix within each hairpin-shaped c-subunit in the ring. Ensembles of monomer and dimers extracted from complete c-rings showed that the coupling between collective ring and the individual subunit motions was independent of the size of the c-ring, which varies between organisms. Molecular determinants were identified by covariance analysis of residue coevolution and structural-alphabet-based local dynamics correlations. The residue coevolution gave a readout of subunit architecture. The dynamic couplings revealed that the hinge for both ring and subunit helix rotations was constructed from the proton-binding site and the adjacent glycine motif (IB-GGGG) in the midmembrane plane. IB-GGGG motifs were linked by long-range couplings across the ring, while intrasubunit couplings connected the motif to the conserved cytoplasmic loop and adjacent segments. The correlation with principal collective motions shows that the couplings underlie both ring rotary and bending motions. Noncontact couplings between IB-GGGG motifs matched the coevolution signal as well as contact couplings. The residue coevolution reflects the physiological importance of the dynamics that may link proton transfer to ring compliance.

Dataset Information

Engineering rotor ring stoichiometries in the ATP synthase.

Publications

Engineering rotor ring stoichiometries in the ATP synthase.

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