Aves S J, Tongue N, Foster A J, Hart E A
School of Biological Sciences, University of Exeter, Perry Road, Exeter EX4 4QG, UK.
Curr Genet. 1998 Sep;34(3):164-71. doi: 10.1007/s002940050382.
The fission yeast cdc23 gene is required for correct DNA replication: cdc23 mutants show reduced rates of DNA synthesis and become elongated after cell-cycle arrest. We have cloned the Schizosaccharomyces pombe cdc23 gene by complementation of the temperature-sensitive phenotype of cdc23-M36 and confirmed the identity of the gene by integrative mapping. Analysis of the DNA sequence reveals that cdc23 can encode a protein of 593 amino acids (Mr=67 kDa) with 22% overall identity and many structural homologies with the product of the Saccharomyces cerevisiae DNA43 (MCM10) gene which is required for correct initiation of DNA synthesis at chromosomal origins of replication. Construction of a cdc23 null allele has established that the cdc23 gene is essential for viability, with cdc23 deletion mutant spores germinating but undergoing arrest with undivided nuclei in the first or second cell cycle. The S. pombe cdc23 gene on an expression plasmid is able to complement the S. cerevisiae dna43-1 mutant. These structural and functional homologies between two distantly related species suggest that cdc23 and DNA43 may represent genes for a conserved essential eukaryotic DNA replication function.
裂殖酵母的cdc23基因对于正确的DNA复制是必需的：cdc23突变体显示出DNA合成速率降低，并且在细胞周期停滞后会变长。我们通过互补cdc23 - M36的温度敏感表型克隆了粟酒裂殖酵母的cdc23基因，并通过整合图谱分析证实了该基因的身份。DNA序列分析表明，cdc23可以编码一个由593个氨基酸组成的蛋白质（Mr = 67 kDa），与酿酒酵母DNA43（MCM10）基因的产物具有22%的总体一致性以及许多结构同源性，DNA43基因是在染色体复制起点正确起始DNA合成所必需的。构建cdc23无效等位基因已证实cdc23基因对于细胞存活至关重要，cdc23缺失突变体的孢子能够萌发，但在第一个或第二个细胞周期中会因细胞核未分裂而停滞。表达质粒上的粟酒裂殖酵母cdc23基因能够互补酿酒酵母dna43 - 1突变体。两个远缘物种之间的这些结构和功能同源性表明，cdc23和DNA43可能代表了一种保守的必需真核生物DNA复制功能的基因。
