Domain compliance and elastic power transmission in rotary FOFl-ATPase

Autor(en): Sielaff, Hendrik
Rennekamp, Henning
Waechter, Andre
Xie, Hao
Hilbers, Florian
Feldbauer, Katrin
Dunn, Stanley D.
Engelbrecht, Siegfried
Junge, Wolfgang 
Stichwörter: 2ND STALK; B-SUBUNIT; elasticity; ENERGY TRANSDUCTION; ESCHERICHIA-COLI; F-1 MOTOR; F-1-ATPASE; F-ATPASE; F1F0-ATP SYNTHASE; MOLECULAR-DYNAMICS; Multidisciplinary Sciences; nanomotor; Science & Technology - Other Topics; VISCOELASTIC DYNAMICS
Erscheinungsdatum: 2008
Herausgeber: NATL ACAD SCIENCES
Journal: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volumen: 105
Ausgabe: 46
Startseite: 17760
Seitenende: 17765
Zusammenfassung: 
The 2 nanomotors of rotary ATP synthase, ionmotive F-O and chemically active F-l, are mechanically coupled by a central rotor and an eccentric bearing. Both motors rotate, with 3 steps in F, and 10-15 in F-O. Simulation by statistical mechanics has revealed that an elastic power transmission is required for a high rate of coupled turnover. Here, we investigate the distribution in the FOFl structure of compliant and stiff domains. The compliance of certain domains was restricted by engineered disulfide bridges between rotor and stator, and the torsional stiffness (kappa) of unrestricted domains was determined by analyzing their thermal rotary fluctuations. A fluorescent magnetic bead was attached to single molecules of F-l and a fluorescent actin filament to FOFl, respectively. They served to probe first the functional rotation and, after formation of the given disulfide bridge, the stochastic rotational motion. Most parts of the enzyme, in particular the central shaft in F-l, and the long eccentric bearing were rather stiff (torsional stiffness kappa > 750 pNnm). One domain of the rotor, namely where the globular portions of subunits gamma and epsilon of F-l contact the c-ring of F-O, was more compliant (kappa congruent to 68 pNnm). This elastic buffer smoothes the cooperation of the 2 stepping motors. It is located were needed, between the 2 sites where the power strokes in F-O and F-l are generated and consumed.
ISSN: 00278424
DOI: 10.1073/pnas.0807683105

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