Estequiometrias da engenharia do anel rotor na ATP sintase: mero acaso, fortuita necessidade ou design inteligente?

terça-feira, agosto 14, 2012

Engineering rotor ring stoichiometries in the ATP synthase

Denys Pogoryelova,1,2, Adriana L. Klyszejkoa,b,2, Ganna O. Krasnoselskaa, Eva-Maria Hellera,3, Vanessa Leonec,3, Julian D. Langerd, Janet Voncka, Daniel J. Müllere, José D. Faraldo-Gómezc,f, and Thomas Meiera,f,1

- Author Affiliations

Departments of aStructural Biology and

dMolecular Membrane Biology,

cTheoretical Molecular Biophysics Group, and

fCluster of Excellence Macromolecular Complexes, Max-Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany;

bBiotechnology Center, Dresden University of Technology, 01307 Dresden, Germany; and

eDepartment of Biosystems Science and Engineering, Swiss Federal Institute of Technology Zürich, 4058 Basel, Switzerland

Edited by Wolfgang Baumeister, Max Planck Institute of Chemistry, Martinsried, Germany, and approved April 25, 2012 (received for review December 6, 2011)


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 c11 ring. Structural and biochemical studies show a direct, specific influence on the c-subunit stoichiometry, revealing c<11 and="and" c12="c12" c13="c13" c14="c14" c="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 with customized ion-to-ATP ratios, by sequence modifications.

alpha helix packing F1Fo ATP synthase membrane protein rotary motor stoichiometry bioenergetics


NOTA DESTE BLOGGER: Cada vez mais os cientistas descobrem complexidade sobre mais complexidades nos sistemas biológicos. As especulações transformistas de Darwin não explicam tanta complexidade!!!