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Engineering of rotor ring stoichiometries in ATP synthase

1 June 2012. In all organisms ATP is the universal energy currency. ATP must be produced continuously by the enzyme F₁Fo-ATP synthase. This membrane protein complex uses the energy stored in a transmembrane ion gradient to power a rotational mechanism, mechanical work which it then translates into chemical energy stored as ATP. The ion-to-ATP ratio describes the number of ions required to synthesize each ATP molecule. Changing the ion-to-ATP ratio in ATP synthase therefore can be compared to shifting gears in an engine.

ATP synthase membrane rotors consist of a ring of c-subunits whose stoichiometry is constant for a given species but variable across different ones. A team led by Thomas Meier and José Faraldo-Goméz at the Max-Planck-Institute of Biophysics now reports the successful alteration of the gear ratio of an ATP synthase by introducing mutations in its amino acid sequence.This study, conducted in collaboration with scientists at the Swiss Federal Institute of Technology in Basel and the Biotechnology Center in Dresden and published in the Proceedings of the National Academy of Sciences of the USA, investigated the importance of c/c-subunit contacts by site-directed mutagenesis of a conserved stretch of glycines (GxGxGxGxG) in a bacterial c₁₁ ring.

Structural and biochemical investigations show a direct, specific influence on the c-subunit stoichiometry, revealing c_<11, c₁₂, c₁₃, c₁₄, 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 c₁₂ instead of c₁₁, 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 . More...

 

Contact

Thomas Meier
Max-Planck-Institute für Biophysik
Max-von-Laue-Str. 3
 60438 Frankfurt am Main
thomas.meier@mpibp-frankfurt.mpg.de
+49 (69) 63033038
   

Full reference
Denys Pogoryelov, Adriana L. Klyszejko, Ganna O. Krasnoselska, Eva-Maria Heller, Vanessa Leone, Julian D. Langer, Janet Vonck, Daniel J. Müller, José D. Faraldo-Gómez and Thomas Meier. 2012. Engineering rotor ring stoichiometries in the ATP synthase . Proceedings of the National Academy of Sciences USA. doi 10.1073/pnas.1120027109