title: A tridecameric c ring of the adenosine triphosphate (ATP) synthase from the thermoalkaliphilic Bacillus sp. strain TA2.A1 facilitates ATP synthesis at low electrochemical proton potential.
abstract: Despite the thermodynamic problem imposed on alkaliphilic bacteria of synthesizing adenosine triphosphate (ATP) against a large inverted pH gradient and consequently a low electrochemical proton potential, these bacteria still utilize a proton-coupled F(1)F(o)-ATP synthase to synthesize ATP. One potential solution to this apparent thermodynamic problem would be the operation of a larger oligomeric c ring, which would raise the ion to ATP ratio, thus facilitating the conversion of a low electrochemical potential into a significant phosphorylation potential. To address this hypothesis, we have purified the oligomeric c ring from the thermoalkaliphilic bacterium Bacillus sp. strain TA2.A1 and determined the number of c-subunits using a novel mass spectrometry method, termed 'laser-induced liquid bead ion desorption' (LILBID). This technique allows the mass determination of non-covalently assembled, detergent-solubilized membrane protein complexes, and hence enables an accurate determination of c ring stoichiometries. We show that the Bacillus sp. strain TA2.A1 ATP synthase harbours a tridecameric c ring. The operation of a c ring with 13 subunits renders the thermodynamic problem of ATP synthesis at alkaline pH less severe and may represent a strategy for ATP synthesis at low electrochemical potential.
authors.affiliation: Max-Planck-Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany. thomas.meier@mpibp-frankfurt.mpg.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Meier
authors.forename: Nina
authors.initials: N
authors.lastname: Morgner
authors.forename: Doreen
authors.initials: D
authors.lastname: Matthies
authors.forename: Denys
authors.initials: D
authors.lastname: Pogoryelov
authors.forename: Stefanie
authors.initials: S
authors.lastname: Keis
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Cook
authors.forename: Peter
authors.initials: P
authors.lastname: Dimroth
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brutschy
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001407:Bacillus / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018892:Proton-Motive Force; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011522:Protons
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; D011522:Protons; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases