THE SCHIZOSACCHAROMYCES-POMBE CDC14 GENE IS REQUIRED FOR SEPTUM FORMATION AND CAN ALSO INHIBIT NUCLEAR DIVISION

A conditional heat-sensitive mutation in the cdc14 gene of the fission yeast Schizosaccharomyces pombe results in failure to form a septum. Cells become highly elongated and multinucleate as growth and nuclear division continue in the absence of cell division. This article descri bes the cloning of the cdc14 gene and the identification of its produc t, a protein of 240 amino acids, p28cdc14. A null allele of the cdc14 gene shows that the gene is essential for septum formation and complet ion of the cell-division cycle. Overexpression of the gene product p28 cdc14, causes cell-cycle arrest in late G2 before mitosis. Cells leaki ng past the block activate p34cdc2 kinase and show condensed chromosom es, but the normal rearrangements of the microtubules and microfilamen ts that are associated with the transition from interphase to mitosis do not occur. Overexpression of p28cdc14 in mutants, in which the timi ng of mitosis is altered, suggests that these effects may be mediated upstream of the mitotic inhibitor wee1. These data are consistent with the idea that p28cdc14 may play a role in both the initiation of mito sis and septum formation and, by doing so, be part of the mechanism th at coordinates these two cell-cycle events.