Rdp1, a novel zinc finger protein, regulates the DNA damage response of rhp51(+) from Schizosaccharomyces pombe

The Schizosaccharomyces pombe DNA repair gene rhp51(+) encodes a RecA-like protein with the DNA-dependent ATPase activity required for homologous reco mbination. The level of the rhp51(+) transcript is increased by a variety o f DNA-damaging agents. Its promoter has two cis-acting DNA damage-responsiv e elements (DREs) responsible for DNA damage inducibility. Here we report i dentification of Rdp1, which regulates rhp51(+) expression through the DRE of rhp51(+). The protein contains a zinc finger and a polyalanine tract sim ilar to ones previously implicated in DNA binding and transactivation or re pression, respectively. In vitro footprinting and competitive binding assay s indicate that the core consensus sequences (NGG/TTG/A) of DRE are crucial for the binding of Rdp1. Mutations of bath DRE1 and DRE2 affected the dama ge-induced expression of rhp51(+), indicating that both DREs are required f or transcriptional activation. In addition, mutations in the DREs significa ntly reduced survival rates after exposure to DNA-damaging agents, demonstr ating that the damage response of rhp51(+) enhances the cellular repair cap acity. Surprisingly, haploid cells containing a complete rdp1 deletion coul d not be recovered, indicating that rdp1(+) is essential far cell viability and implying the existence of other target genes. Furthermore, the DNA dam age-dependent expression of rhp51(+) was significantly reduced in checkpoin t mutants, raising the possibility that Rdp1 may mediate damage checkpoint- dependent transcription of rhp51(+).