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Preliminary Estimation of Rotary Torque Produced by Proton-Motive Force in Fully Functional F0F1-ATPase

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Abstract:

F0F1-ATPase is a rotary molecular motor. It is well known that the rotary torque is generated by ATP hydrolysis in F1 but little is known about how it produces the proton-motive force (PMF) in F0. Here a cross-linking approach was used to estimate the rotary torque produced by PMF. Three mutant E. coli strains were used in this study: SWM92 (δW28L F0F1, as control), MM10 (αP280C γA285C F0F1) and PP2 (αA334C/ δL262C F0F1). The oxidized inner membranes from mutant MM10 having a disulfide bridge in the top of γ subunit exhibited good ATP synthesis activity, while the oxidized PP2 inner membranes having a disulfide bridge in the middle of δ subunit synthesized ATP very poorly. We conclude that the rotary torque generated by PMF is sufficient to uncoil the α-helix in the top of δ subunit (MM10) and to overcome the Ramachandran activation barriers (25-30kJ/mol, i.e. about 40-50pN·nm), but cannot cleave the disulfide bond in the middle of the δ subunit (200 kJ/mol, i.e. 330pN·nm) (PP2). Consequently a preliminary estimation is that the rotary torque generated by PMF in the fully functional F0F1 motor is greater than 40-50pN·nm but less than 330pN·nm.





Keywords: F0F1-ATPase; cross-linking; proton-motive force (PMF); rotary torque

Document Type: Research Article

DOI: http://dx.doi.org/10.2174/092986607779117164

Affiliations: National Laboratory of Biomacromolecules,Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.

Publication date: January 1, 2007

More about this publication?
  • Protein & Peptide Letters publishes short papers in all important aspects of protein and peptide research, including structural studies, recombinant expression, function, synthesis, enzymology, immunology, molecular modeling, drug design etc. Manuscripts must have a significant element of novelty, timeliness and urgency that merit rapid publication. Reports of crystallisation, and preliminary structure determinations of biologically important proteins are acceptable. Purely theoretical papers are also acceptable provided they provide new insight into the principles of protein/peptide structure and function.
ben/ppl/2007/00000014/00000001/art00008
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