title: Schizosaccharomyces pombe pfh1+ encodes an essential 5' to 3' DNA helicase that is a member of the PIF1 subfamily of DNA helicases.
abstract: The Saccharomyces cerevisiae Pif1p DNA helicase is the prototype member of a helicase subfamily conserved from yeast to humans. S. cerevisiae has two PIF1-like genes, PIF1 itself and RRM3, that have roles in maintenance of telomeric, ribosomal, and mitochondrial DNA. Here we describe the isolation and characterization of pfh1+, a Schizosaccharomyces pombe gene that encodes a Pif1-like protein. Pfh1p was the only S. pombe protein with high identity to Saccharomyces Pif1p. Unlike the two S. cerevisiae Pif1 subfamily proteins, the S. pombe Pfh1p was essential. Like Saccharomyces Pif1p, a truncated form of the S. pombe protein had 5' to 3' DNA helicase activity. Point mutations in an invariant lysine residue in the ATP binding pocket of Pfh1p had the same phenotype as deleting pfh1+, demonstrating that the ATPase/helicase activity of Pfh1p was essential. Although mutant spores depleted for Pfh1p proceeded through S phase, they arrested with a terminal cellular phenotype consistent with a postinitiation defect in DNA replication. Telomeric DNA was modestly shortened in the absence of Pfh1p. However, genetic analysis demonstrated that maintenance of telomeric DNA was not the sole essential function of S. pombe Pfh1p.
authors.affiliation: Princeton University, Department of Molecular Biology, Princeton, New Jersey 08544, USA.
authors.forename: Jin-Qiu
authors.initials: JQ
authors.lastname: Zhou
authors.forename: Haiyan
authors.initials: H
authors.lastname: Qi
authors.forename: Vincent P
authors.initials: VP
authors.lastname: Schulz
authors.forename: Maria K
authors.initials: MK
authors.lastname: Mateyak
authors.forename: Ellen K
authors.initials: EK
authors.lastname: Monson
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Zakian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004265:DNA Helicases / Q000235:genetics*; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004268:DNA-Binding Proteins; D006801:Humans; D008969:Molecular Sequence Data; D063146:Polycomb-Group Proteins; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000201:enzymology / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors
chemical_list: D017931:DNA Primers; D004272:DNA, Mitochondrial; D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; C112309:PHF1 protein, human; D063146:Polycomb-Group Proteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C085463:PIF1 protein, S cerevisiae; D004265:DNA Helicases