PROCESSING OF HOLLIDAY JUNCTIONS BY THE ESCHERICHIA-COLI RUVA, RUVB, RUVC AND RECG PROTEINS

Recent work has led to significant advances in our understanding of th e late steps of genetic recombination and the post-replicational repai r of DNA. The RuvA and RuvB proteins have been shown to interact with recombination intermediates and catalyse the branch migration of Holli day junctions. Although both proteins are required for branch migratio n, each plays a defined role with RuvA acting as a specificity factor that directs RuvB (an ATPase) to the junction. The RuvB ATPase provide s the motor for branch migration. The next step is catalysed by RuvC p rotein which recognises Holliday junctions and promotes their resoluti on by endonucleolytic cleavage. New data indicates an alternative path way for Holliday junction processing. This pathway involves RecG, a br anch migration protein which is functionally analogous to RuvAB, and a protein (activated by a rus mutation) which works with RecG to proces s intermediates independently of RuvA, RuvB and RuvC.