TAILIEUCHUNG - Báo cáo Y học: Membrane embedded location of Na+ or H+ binding sites on the rotor ring of F1F0 ATP synthases

Recent crosslinking studies indicated the localization of the coupling ion binding site in the Na + -translocating F1F0 ATP synthase ofIlyobacter tartaricus within the hydrophobic part of the , a membrane embedded H + -binding site is accepted for the H + -trans-locating F1F0 ATP synthase ofEscherichia a more definite analysis, we performed parallax analysis of fluorescence quenching with ATP synthases from both I. tartaricus and E. coli. | Eur. J. Biochem. 269 5581-5589 2002 FEBS 2002 doi Membrane embedded location of Na or H binding sites on the rotor ring of F1F0 ATP synthases Christoph von Ballmoos Thomas Meier and Peter Dimroth Institut fur Mikrobiologie der Eidgenossischen Technischen Hochschule ETH Zentrum Zurich Switzerland Recent crosslinking studies indicated the localization of the coupling ion binding site in the Na -translocating F1F0 ATP synthase of Ilyobacter tartaricus within the hydrophobic part of the bilayer. i k iHarly. a membrane embedded H -binding site is accepted for the H -trans-locating F1F0 ATP synthase of Escherichia coli. For a more definite analysis we performed parallax analysis of fluorescence quenching with ATP synthases from both I. tartaricus and E. coli. Both ATP zaniaasas were specifically labelled at their c subunit sites with N-cyclohexyl-N - 1-pyrenyl carbodiimide a fluorescent analogue of dicyclohexylcarbodiimide and the enzymes were reconstituted into proteoliposomes. Unmg itheta soluble ue nnc-hers or spialabelled phospholipids we observed a deeply membrane embedded binding site which was quantitatively determined for I. tartaricus and E. coli to be A and A from the bilayer center apart data show a conserved topology among enzymes of different species. We fbrtnor Semon-strated the direct accessibility for Na ions to the binding sites in the reconstituted I. tartaricus c11 oligomer in the absence of any other subunits pointing to intrinsic rotor common membrane embedded location of the binding site of ATP synthases suggest a common mechanism for ion transfer across the membrane. Keywords coupling ion binding site parallax analysis membrane localization c subunit ATP synthase. Structurally similar F1F0 ATP synthases are present in mitochondria chloroplasts or eubacteria where they catalyze ATP formation with the energy stored in a transmembrane electrochemical gradient of protons .

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