Characterization of Pfh1 DNA helicase activity and its genetic interaction suggests a role in Okazaki fragment maturation

초록

The Schizosaccharomyces pombe pfh1+ gene was isolated as one of genetic suppressors of cdc24-M38, a temperature-sensitive (ts) mutant allele of cdc24+ that is known to carry out its function most likely via direct interaction with dna2+ encoding a conserved endonuclease-helicase required for Okazaki fragment processing. This observation suggests that pfh1 is required for this process. In a continuing effort to nderstand the role of Pfh1, we determined helicase and ATPase activities associated with this enzyme and investigated genetic interactions between dna2 and Pfh1. This result suggests either (1) that an allele-specific interaction between dna2-C2 and pfh1-R20 or (2) that inactivation of pfh1+ is required for the rescue of defects associated with dna2-C2. In contrast, combination of pfh1-R20 with pol3 or cdc27 resulted in synthetic lethal growth. The genetic interactions above suggest that Pfh1 plays a role in collaboration with Dna2 and pol d during Okazaki fragment processing.