title: Molecular basis of ADP inhibition of vacuolar (V)-type ATPase/synthase.
abstract: Reduction of ATP hydrolysis activity of vacuolar-type ATPase/synthase (V0V1) as a result of ADP inhibition occurs as part of the normal mechanism of V0V1 of Thermus thermophilus but not V0V1 of Enterococcus hirae or eukaryotes. To investigate the molecular basis for this difference, domain-swapped chimeric V1 consisting of both T. thermophilus and E. hirae enzymes were generated, and their function was analyzed. The data showed that the interaction between the nucleotide binding and C-terminal domains of the catalytic A subunit from E. hirae V1 is central to increasing binding affinity of the chimeric V1 for phosphate, resulting in reduction of the ADP inhibition. These findings together with a comparison of the crystal structures of T. thermophilus V1 with E. hirae V1 strongly suggest that the A subunit adopts a conformation in T. thermophilus V1 different from that in E. hirae V1. This key difference results in ADP inhibition of T. thermophilus V1 by abolishing the binding affinity for phosphate during ATP hydrolysis.
authors.affiliation: From the Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto 603-8555, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Kishikawa
authors.forename: Atsuko
authors.initials: A
authors.lastname: Nakanishi
authors.forename: Shou
authors.initials: S
authors.lastname: Furuike
authors.forename: Masatada
authors.initials: M
authors.lastname: Tamakoshi
authors.forename: Ken
authors.initials: K
authors.lastname: Yokoyama
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016983:Enterococcus / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D016963:Thermus thermophilus / Q000201:enzymology* / Q000235:genetics; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D025262:Vacuolar Proton-Translocating ATPases
keywords: ADP Inhibition; ATP Synthase; F1F0 ATPase; Membrane Proteins; Molecular Motors; Vacuolar ATPase