Catalysis of ATP-Dependent Homologous DNA Pairing and Strand Exchange by Yeast RAD51 Protein

Abstract

The RAD51 gene of Saccharomyces cerevisiae is required for genetic recombination and DNA double-strand break repair. Here it is demonstrated that RAD51 protein pairs circular viral single-stranded DNA from phi X 174 or M13 with its respective homologous linear double-stranded form. The product of synapsis between these DNA partners is further processed by RAD51 to yield nicked circular duplex DNA, which indicates that RAD51 can catalyze strand exchange. The pairing and strand exchange reaction requires adenosine triphosphate, a result consistent with the presence of a DNA-dependent adenosine triphosphatase activity in RAD51 protein. Thus, RAD51 is a eukaryotic recombination protein that can catalyze the strand exchange reaction.

Saccharomyces cerevisiae recA homologues RAD51 and DMC1 have both distinct and overlapping roles in meiotic recombination

“…These and other rad51 and dmc1 mutant phenotypes support the view that the roles of Rad51 and Dmc1 are closely related to those of RecA. In vitro studies, thus far only of Rad51 (Shinohara et al 1992;Ogawa et al 1993;Sung 1994;Sung & Robberson 1995;Baumann et al 1996;Gupta et al 1997), also support this idea.…”

Gene targeting is enhanced in human cells overexpressing hRAD51

“…RAD51, a eukaryotic homologue of E. coli recA, seems to play a central role in the process with its DNA pairing and strand exchange activities. 23,24 A direct demonstration for involvement of the vertebrate RAD52 group genes in various types of homologous recombination requires experiments in which expression of a particular gene is either suppressed or elevated in living cells. Thus gene targeting was shown to be impaired in both mouse ES cells and in chicken B cells if RAD54 gene expression was eliminated 25,26 and to a lesser extent, if RAD52 was inactivated.…”

Sensing of DNA non‐homology lowers the initiation of meiotic recomination in yeast

“…This latter step should be important for the formation, stabilization and extension of hybrid DNA. A reduction in the extent of homology at the 3 0 single strand end may lower the efficiency of strand invasion catalysed by the Rad51p strand transfer protein (Sung 1994) or the other RecA-like proteins encoded by RAD55, RAD57 and DMC1 genes (Lovett 1994, and references therein). In in vitro assays of strand exchange catalysed by the Escherichia coli RecA protein, DNA non-homology can impair the early step of strand transfer and can also modify subsequent steps such as the extension or the stability of the heteroduplex DNA (Bianchi & Radding 1983;reviewed in Kowalczykowski & Eggleston 1994).…”