Isolated ε subunit of Bacillus subtilis F1-ATPase binds ATP

Previously, we demonstrated ATP binding to the isolated E subunit of F-1-ATPase from thermophilic Bacillus PS3 [Kato-Yamada Y., Yoshida M. (2003) J. Biol. Chem. 278, 36013]. However, whether it is a general feature of the F. subunit from other sources is yet unclear. Here, using a sensitive method to detect weak interactions between fluorescently labeled F subunit and nucleotide, it was shown that the E subunit of F-1-ATPase from Bacillus subtilis also bound ATP. The dissociation constant for ATP binding at room temperature was calculated to be 2 mM, which may be suitable for sensing cellular ATP concentration in vivo. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.