We are interested in studying the regulation of cell cycle progression by signal transduction events during C. elegans postembryonic development. As the first step of this project, genes that are known to play crucial roles in cell cycle control --
cdc2 serine/threonine kinase and
cdc26/string homologs --were cloned by using PCR. Using a set of degenerate oligos, a ~600 bp fragment was generated off of genomic DNA template and determined to code for a part of
cdc2 homolog. This fragment was then used as a probe to: l) search for cDNA and 2) determine the physical location of the gene in the genome. Approximately 140,000 plaques from a lambdaZap cDNA library (from R. Barstead) were screened: of the five candidates thus isolated, the longest cDNA was found to contain the entire open reading frame. Partial sequence of this cDNA has revealed a high degree of sequence identity between this putative C.elegans
cdc2 and other
cdc2 genes. The only surprise so far has been an Ile to Val substitution in the 'PSTAIR' motif that is absolutely conserved in all
cdc2 genes published to date. This gene, tentatively named ncc-l (for nematode cell cycle), was physically mapped by using the YAC grid filters to right of the cluster on III, and has subsequently been shown to reside within the region covered by cosmid T05G5. A similar approach was taken to clone the C.elegans homolog of
cdc25/string. Preliminary data suggest that we have isolated partial length cDNAs that can encode a gene with significant sequence similarity to other
cdc25 homologs.