Identification of Saccharomyces cerevisiae Genes Whose Deletion Causes Synthetic Effects in Cells with Reduced Levels of the Nuclear Pif1 DNA Helicase. Author Jennifer Stundon, Virginia Zakian Publication Year 2015 Type Journal Article Abstract The multifunctional Saccharomyces cerevisiae Pif1 DNA helicase affects the maintenance of telomeric, ribosomal, and mitochondrial DNAs, suppresses DNA damage at G-quadruplex motifs, influences the processing of Okazaki fragments, and promotes breakage induced replication. All of these functions require the ATPase/helicase activity of the protein. Owing to Pif1's critical role in the maintenance of mitochondrial DNA, pif1Δ strains quickly generate respiratory deficient cells and hence grow very slowly. This slow growth makes it difficult to carry out genome-wide synthetic genetic analysis in this background. Here, we used a partial loss of function allele of PIF1, pif1-m2, which is mitochondrial proficient but has reduced abundance of nuclear Pif1. Although pif1-m2 is not a null allele, pif1-m2 cells exhibit defects in telomere maintenance, reduced suppression of damage at G-quadruplex motifs and defects in breakage induced replication. We performed a synthetic screen to identify nonessential genes with a synthetic sick or lethal relationship in cells with low abundance of nuclear Pif1. This study identified eleven genes that were synthetic lethal (APM1, ARG80, CDH1, GCR1, GTO3, PRK1, RAD10, SKT5, SOP4, UMP1, and YCK1) and three genes that were synthetic sick (DEF1, YIP4, and HOM3) with pif1-m2. Keywords Gene Deletion, Epistasis, Genetic, Phenotype, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, DNA Damage, Gene Expression Regulation, Fungal, DNA Helicases, DNA Replication, Genes, Lethal Journal G3 (Bethesda) Volume 5 Issue 12 Pages 2913-8 Date Published 2015 Oct 19 ISSN Number 2160-1836 DOI 10.1534/g3.115.021139 Alternate Journal G3 (Bethesda) PMCID PMC4683662 PMID 26483010 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML