Hypothesis. RuvA, RuvB and RuvC proteins: Cleaning‐up after recombinational repairs inE. coli

摘要

AbstractAfter the completion of RecA protein‐mediated recombinational repair of daughter‐strand gaps inE. coli, participating chromosomes are held together by Holliday junctions. Until recently, it was not known how the cell disengages the connected chromosomes. Accumulating genetic data suggested that the product of theruvlocus participates in recombinational repair and acts after the formation of Holliday junctions. Molecular characterization of the locus revealed that there are three genes –ruvA, ruvBandruvC; mutations in any one of the genes confer the same phenotype. Recently, the RuvC protein was found to be a Holliday junction resolvase. At first glance, the resolving activity of RuvC alone would appear to be sufficient for the separation of recombining chromosomes. However,in vitrostudies show that the filament of RecA protein is unable to dissociate from the products of the recombination reaction. Thus,in vivo, even if the Holliday junctions are resolved by RuvC, RecA filament must be holding two DNA duplexes together. New findings about enzymatic activities of RuvA and RuvB proteins foster the hope that the machinery for removing the RecA filament from DNA has been