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

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

Volume: 14 Issue: 1

Author(s): Xiaolong Liu, Yuanbo Cui, Chuanfang Chen, Bo Lai, Jiachang Yue and Zhenxi Zhang

Affiliation:

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

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.

Cite this article as:

Liu Xiaolong, Cui Yuanbo, Chen Chuanfang, Lai Bo, Yue Jiachang and Zhang Zhenxi, Preliminary Estimation of Rotary Torque Produced by Proton-Motive Force in Fully Functional F0F1-ATPase, Protein & Peptide Letters 2007; 14 (1) . https://dx.doi.org/10.2174/092986607779117164

DOI https://dx.doi.org/10.2174/092986607779117164	Print ISSN 0929-8665
Publisher Name Bentham Science Publisher	Online ISSN 1875-5305