Miller P J, Johnson D I
Department of Microbiology and Molecular Genetics, Markey Center for Molecular Genetics, University of Vermont, Burlington 05405.
Mol Cell Biol. 1994 Feb;14(2):1075-83. doi: 10.1128/mcb.14.2.1075-1083.1994.
Cdc42p is a highly conserved low-molecular-weight GTPase that is involved in controlling cellular morphogenesis. We have isolated the Cdc42p homolog from the fission yeast Schizosaccharomyces pombe by its ability to complement the Saccharomyces cerevisiae cdc42-1ts mutation. S. pombe Cdc42p is 85% identical in predicted amino acid sequence to S. cerevisiae Cdc42p and 83% identical to the human Cdc42p homolog. The Cdc42p protein fractionates to both soluble and particulate fractions, suggesting that it exists in two cellular pools. We have disrupted the cdc42+ gene and shown that it is essential for growth. The cdc42 null phenotype is an arrest as small, round, dense cells. In addition, we have generated three site-specific mutations, G12V, Q61L, and D118A, in the Cdc42p GTP-binding domains that correspond to dominant-lethal mutations in S. cerevisiae CDC42. In contrast to the S. cerevisiae cdc42 mutations, the S. pombe cdc42 mutant alleles were not lethal when overexpressed. However, the cdc42 mutants did exhibit an abnormal morphological phenotype of large, misshapen cells, suggesting that S. pombe Cdc42p is involved in controlling polarized cell growth.
Cdc42p是一种高度保守的低分子量GTP酶，参与控制细胞形态发生。我们通过其互补酿酒酵母cdc42-1ts突变的能力，从裂殖酵母粟酒裂殖酵母中分离出Cdc42p同源物。粟酒裂殖酵母Cdc42p在预测的氨基酸序列上与酿酒酵母Cdc42p有85%的同一性，与人类Cdc42p同源物有83%的同一性。Cdc42p蛋白可分为可溶性和颗粒性部分，这表明它存在于两个细胞库中。我们破坏了cdc42+基因，并表明它对生长至关重要。cdc42缺失表型是停滞为小的、圆形的、致密的细胞。此外，我们在Cdc42p GTP结合结构域中产生了三个位点特异性突变，即G12V、Q61L和D118A，它们对应于酿酒酵母CDC42中的显性致死突变。与酿酒酵母cdc42突变不同，粟酒裂殖酵母cdc42突变等位基因在过表达时并不致死。然而，cdc42突变体确实表现出大的、畸形细胞的异常形态表型，这表明粟酒裂殖酵母Cdc42p参与控制极化细胞生长。
