7pbm
From Proteopedia
RuvAB branch migration motor complexed to the Holliday junction - RuvB AAA+ state s2 [t2 dataset]
Structural highlights
FunctionRUVB_STRT2 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) (By similarity). Catalyzes branch migration on Holliday junction (HJ) DNA in complex with RuvA from S.typhimurim and ATP (PubMed:36002576). 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. Forms 2 homohexamers on either side of HJ DNA bound by 1 or 2 RuvA tetramers; 4 subunits per hexamer contact DNA at a time. Coordinated motions by a converter formed by DNA-disengaged RuvB subunits stimulates ATP hydrolysis and nucleotide exchange. Immobilization of the converter enables RuvB to convert the ATP-contained energy into a lever motion, pulling 2 nucleotides of DNA out of the RuvA tetramer per ATP hydrolyzed, thus driving DNA branch migration. The RuvB motors rotate together with the DNA substrate, which together with the progressing nucleotide cycle forms the mechanistic basis for DNA recombination by continuous branch migration (PubMed:36002576). Branch migration allows RuvC to scan DNA until it finds its consensus sequence, where it cleaves and resolves cruciform DNA (By similarity).[HAMAP-Rule:MF_00016][1] 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[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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