Mutational analysis of CDC42Sc, a Saccharomyces cerevisiae gene that encodes a putative GTP-binding protein involved in the control of cell polarity
Mutational analysis of CDC42Sc, a Saccharomyces cerevisiae gene that encodes a putative GTP-binding protein involved in the control of cell polarity
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DOI：
10.1128/mcb.11.7.3537-3544.1991
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发表时间：
1991-07
影响因子：
5.3
通讯作者：
M. Ziman;Jeanne M. O'BRIEN;Laurie A. Ouellette;William R. Church;Douglas I. Johnson
中科院分区：
文献类型：
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作者：
M. Ziman;Jeanne M. O'BRIEN;Laurie A. Ouellette;William R. Church;Douglas I. Johnson
酿酒酵母CDC 42基因产物是低分子量GTP结合蛋白ras超家族的成员，参与细胞极性的控制。我们已经分析了三个CDC 42突变（Gly至瓦尔-12，Gln至Leu-61，和Asp至Ala-118）在推定的GTP结合和水解结构域和一个突变（Cys至Ser-188）在推定的异戊二烯化位点的影响。当存在于单倍体cdc 42 - 1 ts或野生型菌株的质粒上时，前三个突变导致显性致死或剂量依赖性显性致死表型。携带质粒（pGAL）的野生型和cdc 42 - 1 ts细胞（pGAL）具有在GAL启动子控制下的CDC 42 Val-12或CDC 42 Leu-61等位基因，其被阻滞为具有伸长的或多个芽的大细胞的新表型。携带pGAL-CDC 42 Ala-118的细胞被捕获为大的、圆形的、未出芽的细胞，使人想起cdc 42 - 1 ts被捕获的细胞。CDC 42 Ala-118突变体与CDC 42 Val-12和CDC 42 Leu-61突变体的不同表型是出乎意料的，因为所有三种类似ras突变体的表型彼此相似。这表明Cdc 42蛋白的生化特性方面不同于Ras蛋白。cdc 42 Ser-188突变基因不能与cdc 42 - 1 ts突变互补，对野生型和cdc 42 - 1 ts均为隐性。在双突变等位基因中，cdc 42 Ser-188突变能够抑制与三个推定的GTP结合和水解突变相关的显性致死性，这表明异戊二烯化是野生型和突变蛋白活性所必需的。
The Saccharomyces cerevisiae CDC42 gene product, a member of the ras superfamily of low-molecular-weight GTP-binding proteins, is involved in the control of cell polarity. We have analyzed the effects of three CDC42 mutations (Gly to Val-12, Gln to Leu-61, and Asp to Ala-118) in the putative GTP-binding and hydrolysis domains and one mutation (Cys to Ser-188) in the putative isoprenylation site. The first three mutations resulted in either a dominant-lethal or dose-dependent dominant-lethal phenotype when present on plasmids in haploid cdc42-1ts or wild-type strains. Both wild-type and cdc42-1ts cells carrying plasmids (pGAL) with either the CDC42Val-12 or CDC42Leu-61 alleles under the control of a GAL promoter were arrested with a novel phenotype of large cells with elongated or multiple buds. Cells carrying pGAL-CDC42Ala-118 were arrested as large, round, unbudded cells reminiscent of cdc42-1ts arrested cells. The different phenotype of the CDC42Ala-118 mutant versus the CDC42Val-12 and CDC42Leu-61 mutants was unexpected since the phenotypes of all three analogous ras mutants were similar to each other. This suggests that aspects of the biochemical properties of the Cdc42 protein differ from those of the Ras protein. The cdc42Ser-188 mutant gene was incapable of complementing the cdc42-1ts mutation and was recessive to both wild-type and cdc42-1ts. In double-mutant alleles, the cdc42Ser-188 mutation was capable of suppressing the dominant lethality associated with the three putative GTP-binding and hydrolysis mutations, suggesting that isoprenylation is necessary for the activity of the wild-type and mutant proteins.