title: Binding of subunit E into the A-B interface of the A(1)A(O) ATP synthase.
abstract: Two of the distinct diversities of the engines A(1)A(O) ATP synthase and F(1)F(O) ATP synthase are the existence of two peripheral stalks and the 24kDa stalk subunit E inside the A(1)A(O) ATP synthase. Crystallographic structures of subunit E have been determined recently, but the epitope(s) and the strength to which this subunit does bind in the enzyme complex are still a puzzle. Using the recombinant A(3)B(3)D complex and the major subunits A and B of the methanogenic A(1)A(O) ATP synthase in combination with fluorescence correlation spectroscopy (FCS) we demonstrate, that the stalk subunit E does bind to the catalytic headpiece formed by the A(3)B(3) hexamer with an affinity (K(d)) of 6.1±0.2μM. FCS experiments with single A and B, respectively, demonstrated unequivocally that subunit E binds stronger to subunit B (K(d)=18.9±3.7μM) than to the catalytic A subunit (K(d)=53.1±4.4). Based on the crystallographic structures of the three subunits A, B and E available, the arrangement of the peripheral stalk subunit E in the A-B interface has been modeled, shining light into the A-B-E assembly of this enzyme.
authors.affiliation: Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Republic of Singapore.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Hunke
authors.forename: Martin
authors.initials: M
authors.lastname: Antosch
authors.forename: Volker
authors.initials: V
authors.lastname: Müller
authors.forename: Gerhard
authors.initials: G
authors.lastname: Grüber
mesh_terms: D025181:ATP Synthetase Complexes / Q000737:chemistry*; D000244:Adenosine Diphosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D002384:Catalysis; D002845:Chromatography / Q000379:methods; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry; D017020:Methanosarcina / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013997:Time Factors
chemical_list: D011994:Recombinant Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D025181:ATP Synthetase Complexes; D008274:Magnesium