Subunit organization and structure in the F0 sector of Escherichia coli F1F0 ATP synthase.
Biochim Biophys Acta
; 1365(1-2): 135-42, 1998 Jun 10.
Article
em En
| MEDLINE
| ID: mdl-9693732
ABSTRACT
In this review, we summarize recent work from our laboratory which establishes the topology and nearest neighbor organization of subunits in the F0 sector of the H+ transporting ATP synthase of Escherichia coli. The E. coli F0 sector is composed of three subunits in an a1b2c12 stoichiometric ratio. Crosslinking experiments with genetically introduced Cys establish a ring-like organization of the 12 c subunits with subunits a and b lying to the outside of the ring. The results are interpreted using an atomic resolution structural model of monomeric subunit c in a chloroform-methanol-water (441, v/v/v) solution, derived by heteronuclear NMR (M.E. Girvin, F. Abildgaard, V. Rastogi, J. Markley, R.H. Fillingame, in press). The crosslinking results validate many predictions of the structural model and confirm a front-to-back-type packing of two subunit c into a functional dimer, as was first predicted from genetic studies. Aspartyl-61, the proton translocating residue, lies at the center of the four transmembrane helices of the functional dimer, rather than at the periphery of the subunit c ring. Subunit a is shown to fold with five transmembrane helices, and a functionally important interaction of transmembrane helix-4 with transmembrane helix-2 of subunit c is established. The single transmembrane helices of the two subunit b dimerize in the membrane. The structure of the transmembrane segment of subunit b is predicted from the NMR structure of the monomeric peptide.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
ATPases Translocadoras de Prótons
/
Escherichia coli
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Estados Unidos