Structure and subunit composition of the RuvAB-Holliday junction complex.
The E. coli RuvA and RuvB proteins, which are involved in the late stages of recombination and the recombinational repair of damaged DNA, bind to Holliday junctions and promote branch migration. We have used electron microscopy and image analysis to examine RuvA and RuvB bound to model Holliday structures. The two hexameric rings of RuvB are oriented in a bipolar manner, so that the large end of each faces the junction. The results suggest a model for branch migration in which DNA is pumped out of the small end of each ring as ATP is hydrolyzed. The same structural polarity has been established for the bacteriophage T7 gp4 replicative helicase. Mass and image analysis of the RuvAB-junction complex suggests that two tetramers of RuvA form a symmetrical sandwich about the plane of the junction.
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Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis 55455, USA.
West
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Egelman
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D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D004265:DNA Helicases; D019915:DNA Primase; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D029968:Escherichia coli Proteins; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron / Q000379:methods; D017348:Microscopy, Electron, Scanning Transmission; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012316:RNA Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C061260:RuvB protein, Bacteria; D004247:DNA; D019915:DNA Primase; D012316:RNA Nucleotidyltransferases; C071059:Holliday junction DNA helicase, E coli; D004265:DNA Helicases