Cloning and sequence analysis of rhp51⁺, a Schizosaccharomyces pombe homolog of the Saccharomyces cerevisiae RAD51 gene

A homolog (rhp51⁺) of the RAD51 gene in Schizosaccharomyces pombe was cloned by screening a Sz. pombe genomic library using the 3'-end of RAD51 from Saccharomyces cerevisiae as a probe. As in S. cerevisiae, the sequence of rhp51⁺ showed two MluI cell-cycle boxes and a putative DNA damage-responsive element in its upstream region. The open reading frame codes for a 365-amino-acid (aa) polypeptide with an estimated molecular mass of 40 555 Da. The deduced aa sequence shows 27, 66, 75 and 80% identity with Escherichia coli RecA, S. cerevisiae Rad51 and the Rad51 homologs from chicken and humans, respectively. The aa sequence encoded by rhp51⁺ contains A- and B-type nucleotide-binding consensus sequences, as found in other RAD51 homologs. Northern blot analysis showed that rhp51⁺ encodes a 1.7-kb transcript. Methyl methanesulfonate treatment increased the level of this transcript three- to fivefold. Southern hybridization analysis suggests that a single copy of rhp51⁺ exists in the Sz. pombe genome.