8efy
Structure of double homo-hexameric AAA+ ATPase RuvB motors
Structural highlights
FunctionRUVB_THET8 The RuvA-RuvB complex in the presence of ATP renatures cruciform structure in supercoiled DNA with palindromic sequence, indicating that it may promote strand exchange reactions in homologous recombination. RuvAB is a helicase that mediates the Holliday junction migration by localized denaturation and reannealing. RuvB is a Mg(2+)-dependent, DNA-dependent ATPase with an equal preference for supercoiled and linear duplex DNA. It can promote Holliday junction migration alone.[1] Publication Abstract from PubMedThe Holliday junction (HJ) is a DNA intermediate of homologous recombination, involved in many fundamental physiological processes. RuvB, an ATPase motor protein, drives branch migration of the Holliday junction with a mechanism that had yet to be elucidated. Here we report two cryo-EM structures of RuvB, providing a comprehensive understanding of HJ branch migration. RuvB assembles into a spiral staircase, ring-like hexamer, encircling dsDNA. Four protomers of RuvB contact the DNA backbone with a translocation step size of 2 nucleotides. The variation of nucleotide-binding states in RuvB supports a sequential model for ATP hydrolysis and nucleotide recycling, which occur at separate, singular positions. RuvB's asymmetric assembly also explains the 6:4 stoichiometry between the RuvB/RuvA complex, which coordinates HJ migration in bacteria. Taken together, we provide a mechanistic understanding of HJ branch migration facilitated by RuvB, which may be universally shared by prokaryotic and eukaryotic organisms. Molecular mechanisms of Holliday junction branch migration catalyzed by an asymmetric RuvB hexamer.,Rish AD, Shen Z, Chen Z, Zhang N, Zheng Q, Fu TM Nat Commun. 2023 Jun 15;14(1):3549. doi: 10.1038/s41467-023-39250-6. PMID:37322069[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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