7pbu
RuvAB branch migration motor complexed to the Holliday junction - RuvA-HJ core [t2 dataset]
Structural highlights
FunctionA0A0M0QTS9_SALTM The RuvA-RuvB-RuvC complex processes Holliday junction (HJ) DNA during genetic recombination and DNA repair, while the RuvA-RuvB complex plays an important role in the rescue of blocked DNA replication forks via replication fork reversal (RFR). RuvA specifically binds to HJ cruciform DNA, conferring on it an open structure. The RuvB hexamer acts as an ATP-dependent pump, pulling dsDNA into and through the RuvAB complex. HJ branch migration allows RuvC to scan DNA until it finds its consensus sequence, where it cleaves and resolves the cruciform DNA.[HAMAP-Rule:MF_00031] Publication Abstract from PubMedThe Holliday junction is a key intermediate formed during DNA recombination across all kingdoms of life(1). In bacteria, the Holliday junction is processed by two homo-hexameric AAA+ ATPase RuvB motors, which assemble together with the RuvA-Holliday junction complex to energize the strand-exchange reaction(2). Despite its importance for chromosome maintenance, the structure and mechanism by which this complex facilitates branch migration are unknown. Here, using time-resolved cryo-electron microscopy, we obtained structures of the ATP-hydrolysing RuvAB complex in seven distinct conformational states, captured during assembly and processing of a Holliday junction. Five structures together resolve the complete nucleotide cycle and reveal the spatiotemporal relationship between ATP hydrolysis, nucleotide exchange and context-specific conformational changes in RuvB. Coordinated motions in a converter formed by DNA-disengaged RuvB subunits stimulate hydrolysis and nucleotide exchange. Immobilization of the converter enables RuvB to convert the ATP-contained energy into a lever motion, which generates the pulling force driving the branch migration. We show that RuvB motors rotate together with the DNA substrate, which, together with a progressing nucleotide cycle, forms the mechanistic basis for DNA recombination by continuous branch migration. Together, our data decipher the molecular principles of homologous recombination by the RuvAB complex, elucidate discrete and sequential transition-state intermediates for chemo-mechanical coupling of hexameric AAA+ motors and provide a blueprint for the design of state-specific compounds targeting AAA+ motors. Mechanism of AAA+ ATPase-mediated RuvAB-Holliday junction branch migration.,Wald J, Fahrenkamp D, Goessweiner-Mohr N, Lugmayr W, Ciccarelli L, Vesper O, Marlovits TC Nature. 2022 Sep;609(7927):630-639. doi: 10.1038/s41586-022-05121-1. Epub 2022 , Aug 24. PMID:36002576[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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