1L2P

ATP Synthase b Subunit Dimerization Domain

Summary for 1L2P

• Entry DOI: 10.2210/pdb1l2p/pdb
• Descriptor: ATP Synthase B Chain (2 entities in total)
• Functional Keywords: alpha helix, hydrolase
• Biological source: Escherichia coli
• Cellular location: Cell inner membrane ; Single-pass membrane protein : P0ABA0
• Total number of polymer chains: 1
• Total formula weight: 7058.98

Authors

Del Rizzo, P.A.,Dunn, S.D.,Bi, Y.,Shilton, B.H. (deposition date: 2002-02-22, release date: 2002-06-05, Last modification date: 2024-02-14)

Primary citation

Del Rizzo, P.A.,Bi, Y.,Dunn, S.D.,Shilton, B.H.
The "second stalk" of Escherichia coli ATP synthase: structure of the isolated dimerization domain.
Biochemistry, 41:6875-6884, 2002

PubMed Abstract: 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.

PubMed: 12022893
DOI: 10.1021/bi025736i

Experimental method

X-RAY DIFFRACTION (1.55 Å)