title: Isolated epsilon subunit of thermophilic F1-ATPase binds ATP.
abstract: F1-ATPase, a soluble part of the F0F1-ATP synthase, has subunit structure alpha3beta3gammadeltaepsilon in which nucleotide-binding sites are located in the alpha and beta subunits and, as believed, in none of the other subunits. However, we report here that the isolated epsilon subunit of F1-ATPase from thermophilic Bacillus strain PS3 can bind ATP. The binding was directly demonstrated by isolating the epsilon subunit-ATP complex with gel filtration chromatography. The binding was not dependent on Mg2+ but was highly specific for ATP; however, ADP, GTP, UTP, and CTP failed to bind. The epsilon subunit lacking the C-terminal helical hairpin was unable to bind ATP. Although ATP binding to the isolated epsilon subunits from other organisms has not been detected under the same conditions, a possibility emerges that the epsilon subunit acts as a built in cellular ATP level sensor of F0F1-ATP synthase.
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kato-Yamada
authors.forename: Masasuke
authors.initials: M
authors.lastname: Yoshida
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014466:Ultraviolet Rays; D000097795:ATPase Inhibitory Protein
chemical_list: D000255:Adenosine Triphosphate; D011506:Proteins; D011994:Recombinant Proteins; D000097795:ATPase Inhibitory Protein