title: Direct evidence that a conserved arginine in RuvB AAA+ ATPase acts as an allosteric effector for the ATPase activity of the adjacent subunit in a hexamer.
abstract: The Escherichia coli RuvA and RuvB protein complex promotes branch migration of Holliday junctions during recombinational repair and homologous recombination and at stalled replication forks. The RuvB protein belongs to the AAA(+) (ATPase associated with various cellular activities) ATPase family and forms a hexameric ring in an ATP-dependent manner. Studies on the oligomeric AAA(+) class ATPases suggest that a conserved arginine residue is located in close proximity to the ATPase site of the adjacent subunit and plays an essential role during ATP hydrolysis. This study presents direct evidence that Arg-174 of RuvB allosterically stimulates the ATPase of the adjacent subunit in a RuvB hexamer. RuvBR174A shows a dominant negative phenotype for DNA repair in vivo and inhibits the branch migration catalyzed by wild-type RuvB. A dominant negative phenotype was also observed with RuvBK68A (Walker A mutation). RuvB K68A-R174A double mutant demonstrates a more severe dominant negative effect than the single mutants RuvB K68A or R174A. Moreover, although RuvB K68A and R174A are totally defective in ATPase activity, ATPase activity is restored when these two mutant proteins are mixed at a 1:1 ratio. These results suggest that each of the two mutants has distinct functional defects and that restoration of the ATPase activity is brought by complementary interaction between the mutant subunits in the heterohexamers. This study demonstrates that R174 plays an intermolecular catalytic role during ATP hydrolysis by RuvB. This role may be a general feature of the oligomeric AAA/AAA(+) ATPases.
authors.affiliation: Department of Molecular Microbiology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hishida
authors.forename: Yong-Woon
authors.initials: YW
authors.lastname: Han
authors.forename: Satoko
authors.initials: S
authors.lastname: Fujimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwasaki
authors.forename: Hideo
authors.initials: H
authors.lastname: Shinagawa
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D001120:Arginine / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D017124:Conserved Sequence / Q000235:genetics; D004265:DNA Helicases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins; D006868:Hydrolysis; D008956:Models, Chemical; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D021122:Protein Subunits; C061260:RuvB protein, Bacteria; D000255:Adenosine Triphosphate; D001120:Arginine; C071059:Holliday junction DNA helicase, E coli; D000251:Adenosine Triphosphatases; D004265:DNA Helicases