1b9u
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(New page: 200px<br /><applet load="1b9u" size="450" color="white" frame="true" align="right" spinBox="true" caption="1b9u" /> '''MEMBRANE DOMAIN OF THE SUBUNIT B OF THE E.CO...)
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Revision as of 09:22, 20 November 2007
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MEMBRANE DOMAIN OF THE SUBUNIT B OF THE E.COLI ATP SYNTHASE
Overview
The structure of the N-terminal transmembrane domain (residues 1-34) of, subunit b of the Escherichia coli F0F1-ATP synthase has been solved by, two-dimensional 1H NMR in a membrane mimetic solvent mixture of, chloroform/methanol/H2O (4:4:1). Residues 4-22 form an alpha-helix, which, is likely to span the hydrophobic domain of the lipid bilayer to anchor, the largely hydrophilic subunit b in the membrane. The helical structure, is interrupted by a rigid bend in the region of residues 23-26 with, alpha-helical structure resuming at Pro-27 at an angle offset by 20, degrees from the transmembrane helix. In native subunit b, the hinge, region and C-terminal alpha-helical segment would connect the, transmembrane helix to the cytoplasmic domain. The transmembrane domains, of the two subunit b in F0 were shown to be close to each other by, cross-linking experiments in which single Cys were substituted for, residues 2-21 of the native subunit and b-b dimer formation tested after, oxidation with Cu(II)(phenanthroline)2. Cys residues that formed disulfide, cross-links were found with a periodicity indicative of one face of an, alpha-helix, over the span of residues 2-18, where Cys at positions 2, 6, and 10 formed dimers in highest yield. A model for the dimer is presented, based upon the NMR structure and distance constraints from the, cross-linking data. The transmembrane alpha-helices are positioned at a 23, degrees angle to each other with the side chains of Thr-6, Gln-10, Phe-14, and Phe-17 at the interface between subunits. The change in direction of, helical packing at the hinge region may be important in the functional, interaction of the cytoplasmic domains.
About this Structure
1B9U is a Single protein structure of sequence from [1]. Active as H(+)-transporting two-sector ATPase, with EC number 3.6.3.14 Full crystallographic information is available from OCA.
Reference
Structure of the membrane domain of subunit b of the Escherichia coli F0F1 ATP synthase., Dmitriev O, Jones PC, Jiang W, Fillingame RH, J Biol Chem. 1999 May 28;274(22):15598-604. PMID:10336456
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