The Schizosaccharomyces pombe rfc3⁺ gene encodes a homologue of the human hRFC36 and Saccharomyces cerevisiae Rfc3 subunits of replication factor C

In the yeasts Saccharomyces cevevisiae and Schizosaccharomyces pombe replication factor C (RF-C) plays key roles both in chromosomal DNA replication and in DNA replication checkpoint function. At the replication fork, the five-subunit RF-C complex functions to load the trimeric polymerase accessory factor PCNA onto DNA. PCNA then acts as a sliding clamp tethering Pol delta to the DNA to maximise its processivity. Here we describe the cloning of the S. pombe rfc3(+) gene, encoding a homologue of the S. cevevisiae Rfc3 and human hRFC36 proteins. The 1026 bp rfc3(+) ORF is interrupted by five introns, ranging in size from 49 to 165 bp. The spliced ORF is predicted to encode a 342 amino-acid protein that is approximately 50% identical at the amino acid sequence level to the S. cevevisiae Rfc3 and human hRFC36 proteins. As expected, S. pombe rfc3(+) is an essential gene, with rfc3 Delta cells being defective for DNA replication. Loss of rfc3(+) function can be rescued by heterologous expression of either the S. cerevisiae Rfc3 or human hRFC36 proteins in S. pombe.