tailieunhanh - Báo cáo khoa học: Structural evidence for a constant c11 ring stoichiometry in the sodium F-ATP synthase

The Na + -dependent F-ATP synthases ofIlyobacter tartaricusandPropioni-genium modestum contain membrane-embedded ring-shaped c subunit assemblies with a stoichiometry of 11. Subunit c from either organism was overexpressed in Escherichia coliusing a plasmid containing the corres-ponding gene, extracted from the membrane using detergent and then puri-fied. | iFEBS Journal Structural evidence for a constant C11 ring stoichiometry in the sodium F-ATP synthase Thomas Meier1 Jinshu Yu2 Thomas Raschle1 Fabienne Henzen1 Peter Dimroth1 and Daniel J. Muller2 1 Institut fur Mikrobiologie Eidgenossische Technische Hochschule Zurich Switzerland 2 Center of Biotechnology University of Technology Dresden Germany Keywords atomic force microscopy c ring stoichiometry F-ATP synthase Ilyobacter tartaricus Propionigenium modestum Correspondence T. Meier Institut for Mikrobiologie Eidgenossische Technische Hochschule Zurich ETH-Honggerberg Wolfgang-Pauli-Str. 10 CH 8093 Zurich Switzerland Fax 41 44 6321378 Tel 41 44 6325523 E-mail meier@ Received 27 June 2005 accepted 26 August 2005 doi The Na -dependent F-ATP synthases of Ilyobacter tartaricus and Propioni-genium modestum contain membrane-embedded ring-shaped c subunit assemblies with a stoichiometry of 11. Subunit c from either organism was overexpressed in Escherichia coli using a plasmid containing the corresponding gene extracted from the membrane using detergent and then purified. Subsequent analyses by SDS PAGE revealed that only a minor portion of the c subunits had assembled into stable rings while the majority migrated as monomers. The population of rings consisted mainly of c11 but more slowly migrating assemblies were also found which might reflect other c ring stoichiometries. We show that they consisted of higher aggregates of homogeneous cn rings and or assemblies of c11 rings and single c monomers. Atomic force microscopy topographs of c rings reconstituted into lipid bilayers showed that the c ring assemblies had identical diameters and that stoichiometries throughout all rings resolved at high resolution. This finding did not depend on whether the rings were assembled into crystalline or densely packed assemblies. Most of these rings represented completely assembled undecameric complexes. Occasionally rings lacking a .

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