Open AccessProton transfer is rate-limiting for translocation of precursor proteins by the Escherichia coli translocase.
Author(s) -
Arnold J.M. Driessen,
William Wickner
Publication year - 1991
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.88.6.2471
Subject(s) - chromosomal translocation , translocase , biophysics , transmembrane protein , chemistry , chemiosmosis , electrochemical gradient , proton , escherichia coli , biochemistry , membrane , biology , atp synthase , receptor , enzyme , gene , physics , quantum mechanics
The protonmotive force stimulates translocation in vivo, in crude in vitro reactions, and in a purified, reconstituted reaction. Translocation activity is a function of the pH at the inner face of the membrane. Both the transmembrane pH gradient and the transmembrane electrical potential stimulate translocation. A late-stage translocation intermediate of the proOmpA preprotein completes its translocation in the absence of ATP when a protonmotive force is imposed. This completion of translocation is retarded by a factor of greater than 3 in deuterium oxide relative to water, demonstrating that translocation involves proton-transfer reactions in rate-limiting steps.