1l2p
ATP Synthase b Subunit Dimerization Domain
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OverviewOverview
The b subunit of E. coli F(0)F(1)-ATPase links the peripheral F(1), subunits to the membrane-integral F(0) portion and functions as a, "stator", preventing rotation of F(1). The b subunit is present as a dimer, in ATP synthase, and residues 62-122 are required to mediate dimerization., To understand how the b subunit dimer is formed, we have studied the, structure of the isolated dimerization domain, b(62-122). Analytical, ultracentrifugation and solution small-angle X-ray scattering (SAXS), indicate that the b(62-122) dimer is extremely elongated, with a, frictional ratio of 1.60, a maximal dimension of 95 A, and a radius of, gyration of 27 A, values that are consistent with an alpha-helical, coiled-coil structure. The crystal structure of b(62-122) has been solved, and refined to 1.55 A. The protein crystallized as an isolated, monomeric, alpha helix with a length of 90 A. Combining the crystal structure of, monomeric b(62-122) with SAXS data from the dimer in solution, we have, constructed a model for the b(62-122) dimer in which the two helices form, a coiled coil with a right-handed superhelical twist. Analysis of b, sequences from E. coli and other prokaryotes indicates conservation of an, undecad repeat, which is characteristic of a right-handed coiled coil and, consistent with our structural model. Mutation of residue Arg-83, which, interrupts the undecad pattern, to alanine markedly stabilized the dimer, as expected for the proposed two-stranded, right-handed coiled-coil, structure.
About this StructureAbout this Structure
1L2P is a Single protein structure of sequence from Escherichia coli. The following page contains interesting information on the relation of 1L2P with [ATP Synthase]. Active as Iron-chelate-transporting ATPase, with EC number 3.6.3.34 Full crystallographic information is available from OCA.
ReferenceReference
The "second stalk" of Escherichia coli ATP synthase: structure of the isolated dimerization domain., Del Rizzo PA, Bi Y, Dunn SD, Shilton BH, Biochemistry. 2002 May 28;41(21):6875-84. PMID:12022893
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