CLONING THE RAD51 HOMOLOG OF SCHIZOSACCHAROMYCES-POMBE

The RAD51 gene of Saccharomyces cerevisiae encodes a RecA like protein , which is involved in the recombinational repair of double strand bre aks. We have isolated the RAD51 homologue, rhp51+, of the distantly re leated yeast strain Schizosaccharomyces pombe by heterologous hybridiz ation. DNA sequence analysis of the rhp51+ gene revealed an open readi ng frame of 365 amino acids. Comparison of the amino acid sequences of RAD51 and rhp51+ showed a high level of conservation: 69% identical a mino acids. There are two MIuI sites in the upstream region which may be associated with cell cycle regulation of the rhp51+ gene. The rhp51 + null allele, constructed by disruption of the coding region, is extr emely sensitive to X-rays, indicating that the rhp51+ gene, like RAD51 , is also involved in the repair of X-ray damage. The structural and f unctional homology between rhp51+ and RAD51 suggests evolutionary cons ervation of certain steps in the recombinational repair pathway.