title: The second stalk of Escherichia coli ATP synthase.
abstract: Two stalks link the F(1) and F(0) sectors of ATP synthase. The central stalk contains the gamma and epsilon subunits and is thought to function in rotational catalysis as a rotor driving conformational changes in the catalytic alpha(3)beta(3) complex. The two b subunits and the delta subunit associate to form b(2)delta, a second, peripheral stalk extending from the membrane up the side of alpha(3)beta(3) and binding to the N-terminal regions of the alpha subunits, which are approx. 125 A from the membrane. This second stalk is essential for binding F(1) to F(0) and is believed to function as a stator during rotational catalysis. In vitro, b(2)delta is a highly extended complex held together by weak interactions. Recent work has identified the domains of b which are essential for dimerization and for interaction with delta. Disulphide cross-linking studies imply that the second stalk is a permanent structure which remains associated with one alpha subunit or alphabeta pair. However, the weak interactions between the polypeptides in b(2)delta pose a challenge for the proposed stator function.
authors.affiliation: Department of Biochemistry, University of Western Ontario, N6A 5C1, London, Ont., Canada. sdunn@julian.uwo.ca
authors.forename: S D
authors.initials: SD
authors.lastname: Dunn
authors.forename: D T
authors.initials: DT
authors.lastname: McLachlin
authors.forename: M
authors.initials: M
authors.lastname: Revington
mesh_terms: D025181:ATP Synthetase Complexes; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology*; D008958:Models, Molecular; D020409:Molecular Motor Proteins; D009097:Multienzyme Complexes / Q000737:chemistry; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000737:chemistry*
chemical_list: D004220:Disulfides; D020409:Molecular Motor Proteins; D009097:Multienzyme Complexes; D025181:ATP Synthetase Complexes; D017856:Phosphotransferases (Phosphate Group Acceptor); D006180:Proton-Translocating ATPases