The role of RuvA octamerization for RuvAB function in vitro and in vivo.
J BIOL CHEM
3365 - 3375.
RuvA plays an essential role in branch migration of the Holliday junction by RuvAB as part of the RuvABC pathway for processing Holliday junctions in Escherichia coli. Two types of RuvA-Holliday junction complexes have been characterized: 1) complex I containing a single RuvA tetramer and 2) complex H in which the junction is sandwiched between two RuvA tetramers. The functional differences between the two forms are still not clear. To investigate the role of RuvA octamerization, we introduced three amino acid substitutions designed to disrupt the E. coli RuvA tetramer-tetramer interface as identified by structural studies. The mutant RuvA was tetrameric and interacted with both RuvB and junction DNA but, as predicted, formed complex I only at protein concentrations up to 500 nm. We present biochemical and surface plasmon resonance evidence for functional and physical interactions of the mutant RuvA with RuvB and RuvC on synthetic junctions. The mutant RuvA with RuvB showed DNA helicase activity and could support branch migration of synthetic four-way and three-way junctions. However, junction binding and the efficiency of branch migration of four-way junctions were affected. The activity of the RuvA mutant was consistent with a RuvAB complex driven by one RuvB hexamer only and lead us to propose that one RuvA tetramer can only support the activity of one RuvB hexamer. Significantly, the mutant failed to complement the UV sensitivity of E. coli DeltaruvA cells. These results indicate strongly that RuvA octamerization is essential for the full biological activity of RuvABC.
|Title:||The role of RuvA octamerization for RuvAB function in vitro and in vivo|
|Open access status:||An open access publication|
|Keywords:||ESCHERICHIA-COLI RUVA, HOLLIDAY JUNCTION RESOLVASE, MYCOBACTERIUM-LEPRAE RUVA, MIGRATION MOTOR PROTEIN, DNA HELICASE ACTIVITY, BRANCH MIGRATION, CRYSTAL-STRUCTURE, HOMOLOGOUS RECOMBINATION, SCHIZOSACCHAROMYCES-POMBE, RECOGNITION PROTEIN|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Life Sciences > Biosciences (Division of) > Structural and Molecular Biology
UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Medicine (Division of)
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