F1-ATPase changes its conformations upon phosphate release.
Motor proteins, myosin, and kinesin have gamma-phosphate sensors in the switch II loop that play key roles in conformational changes that support motility. Here we report that a rotary motor, F1-ATPase, also changes its conformations upon phosphate release. The tryptophan mutation was introduced into Arg-333 in the beta subunit of F1-ATPase from thermophilic Bacillus PS3 as a probe of conformational changes. This residue interacts with the switch II loop (residues 308-315) of the beta subunit in a nucleotide-bound conformation. The addition of ATP to the mutant F1 subcomplex alpha3beta(R333W)3gamma caused transient increase and subsequent decay of the Trp fluorescence. The increase was caused by conformational changes on ATP binding. The rate of decay agreed well with that of phosphate release monitored by phosphate-binding protein assays. This is the first evidence that the beta subunit changes its conformation upon phosphate release, which may share a common mechanism of exerting motility with other motor proteins.
Masaike
Tomoko
T
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503, Japan.
Muneyuki
Eiro
E
Noji
Hiroyuki
H
Kinosita
Kazuhiko
K
Yoshida
Masasuke
M
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001120:Arginine / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D006868:Hydrolysis; D008956:Models, Chemical; D008958:Models, Molecular; D010710:Phosphates; D011485:Protein Binding; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013997:Time Factors
D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001120:Arginine; D006180:Proton-Translocating ATPases