Genetic and molecular analysis of DNA43 and DNA52: Two new cell‐cycle genes in Saccharomyces cerevisiae

Two Saccharomyces cerevisiae genes previously unknown to be required for DNA synthesis have ben identified by screening a collection of temperature‐sensitive mutants. The effects of mutations in DNA43 and DNA52 on the rate of S phase DNA synthesis were detected by monitoring DNA synthesis in synchronous populations that were obtained by isopycnic density centrifugation. dna43‐1 and dna52‐1 cells undergo cell‐cycle arrest at the restrictive temperature (37°C), exhibiting a large‐budded terminal phenotype; the nuclei of arrested cells are located at the neck of the bud have failed to undergo DNA replication. These phenotypes suggest that DNA43 and DNA52 are required for entry into or completion of S phase. DNA43 and DNA52 were cloned by their abilities to suppress the temperature‐sensitive lethal phenotypes of dna43‐1and dna52‐1 cells, respectively. DNA sequence analysis suggested that DNA43 and DNA52 encode proteins of 59.6 and 80.6 kDa, respectively. Both DNA43 and DNA52 are essential for viability and genetic mapping experiments indicate that they represent previously unidentified genes: DNA43 is located on chromosome IX, 32 cM distal from his5 and DNA52 is located on chromosome IV, 0.9 cM from cdc34.