Crossover junction endodeoxyribonuclease RuvC is also called Holliday junction resolvase RuvC. It is part of the RuvABC pathway in Escherichia coli and other Gram-negative bacteria that is involved in processing Holliday junctions, which are formed by the reciprocal exchange of strands between two DNA duplexes. Holliday junction resolvases (HJRs) are endonucleases that specifically resolve Holliday junction DNA intermediates during homologous recombination. RuvC is thought to bind either on the open, DNA exposed face of a single RuvA tetramer, or to replace one of the two tetramers. Binding is proposed to be mediated by an unstructured loop on RuvC, which becomes structured on binding RuvA. RuvC can be bound to the complex in either orientation, therefore resolving Holliday junctions in either a horizontal or vertical manner. HJRs occur in archaea, bacteria, and in the mitochondria of certain fungi. These are referred to as the RuvC family of Holliday junction resolvases, RuvC being the Escherichia coli HJR. RuvC and its orthologs are homodimers and display structural similarity to RNase H and Hsp70.
Comment:Escherichia coli RuvC resolvase (1HJR) contains four acidic amino acids, D7, E66, D138, and D141, which play a critical role in the cleavage of Holliday junctions.
Comment:by site-directed mutagenesis
Comment:active site is located at base of DNA binding cleft
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