ATP-dependent rotation of mutant ATP synthases defective in proton transport.
During ATP hydrolysis, the gammaepsilon c10 complex (gamma and epsilon subunits and a c subunit ring formed from 10 monomers) of F0F1 ATPase (ATP synthase) rotates relative to the alpha3beta3delta ab2 complex, leading to proton transport through the interface between the a subunit and the c subunit ring. In this study, we replaced the two pertinent residues for proton transport, cAsp-61 and aArg-210 of the c and a subunits, respectively. The mutant enzymes exhibited lower ATPase activities than that of the wild type but exhibited ATP-dependent rotation in planar membranes, in which their original assemblies are maintained. The mutant enzymes were defective in proton transport, as shown previously. These results suggest that proton transport can be separated from rotation in ATP hydrolysis, although rotation ensures continuous proton transport by bringing the cAsp-61 and aArg-210 residues into the correct interacting positions.
Hosokawa
Hiroyuki
H
Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
Nakanishi-Matsui
Mayumi
M
Kashiwagi
Sachiko
S
Fujii-Taira
Ikuko
I
Hayashi
Kazuhiro
K
Iwamoto-Kihara
Atsuko
A
Wada
Yoh
Y
Futai
Masamitsu
M
D000255:Adenosine Triphosphate / Q000378:metabolism*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D016296:Mutagenesis; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D011522:Protons
D011522:Protons; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases