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Durham University

Department of Biosciences


Publication details for Dr Gary Sharples

Sharples, G.J., Corbett, L.M. & Graham, I.R. (1998). Lambda Rap protein is a structure-specific endonuclease involved in phage recombination. Proc Natl Acad Sci USA 95: 13507-13512.

Author(s) from Durham


Bacteriophage lambda encodes a number of genes involved in the recombinational repair of DNA double-strand breaks. The product of one of these genes, rap, has been purified. Truncated Rap proteins that copurify with the full-length form are derived, at least in part, from a rho-dependent transcription terminator located within its coding sequence. Full-length and certain truncated Rap polypeptides bind preferentially to branched DNA substrates, including synthetic Holliday junctions and D-loops. In the presence of manganese ions, Rap acts as an endonuclease that cleaves at the branch point of Holliday and D-loop substrates. It shows no obvious sequence preference or symmetry of cleavage on a Holliday junction. The biochemical analysis of Rap gives an insight into how recombinants could be generated by the nicking of a D-loop without the formation of a classical Holliday junction.