tailieunhanh - Báo cáo khoa học: Arginine-induced conformational change in the c-ring ⁄a-subunit interface of ATP synthase

The rotational mechanism of ATP synthases requires a unique interface between the statorasubunit and the rotating c-ring to accommodate sta-bility and smooth rotation simultaneously. The recently publishedc-ring crystal structure of the ATP synthase ofIlyobacter tartaricusrepresents the conformation in the absence of subunita. | ỊFEBS Journal Arginine-induced conformational change in the c-ring a-subunit interface of ATP synthase Thomas Vorburger1 Judith Zingg Ebneter1 Alexander Wiedenmann1 Damien Merger1 Gerald Weber1 Kay Diederichs2 Peter Dimroth1 and Christoph von Ballmoos1 1 Institut fur Mikrobiologie ETH Zurich Honggerberg Switzerland 2 Fachbereich Biologie Universitat Konstanz M656 Germany Keywords a c interface ATP synthase c-ring cysteine cross-linking ion-binding pocket Correspondence C. von Ballmoos Institut fur Mikrobiologie ETH Zurich Honggerberg Wolfgang-Pauli-Str. 10 CH-8093 Zurich Switzerland Fax 41 44 6321378 Tel 41 44 6323830 E-mail ballmoos@ Received 23 January 2008 revised 29 February 2008 accepted 3 March 2008 doi The rotational mechanism of ATP synthases requires a unique interface between the stator a subunit and the rotating c-ring to accommodate stability and smooth rotation simultaneously. The recently published c-ring crystal structure of the ATP synthase of Ilyobacter tartaricus represents the conformation in the absence of subunit a. However in order to understand the dynamic structural processes during ion translocation studies in the presence of subunit a are required. Here by intersubunit Cys-Cys crosslinking the relative topography of the interacting helical faces of subunits a and c from the I. tartaricus ATP synthase has been mapped. According to these data the essential stator arginine aR226 is located between the c-ring binding pocket and the cytoplasm. Furthermore the spatially vicinal residues cT67C and cG68C in the isolated c-ring structure yielded largely asymmetric cross-linking products with aN230C of subunit a suggesting a small but significant conformational change of binding-site residues upon contact with subunit a. The conformational change was dependent on the positive charge of the stator arginine or the aR226H substitution. Energyminimization calculations revealed possible modes for the .