Singularity in budding: A role for the evolutionarily conserved small GTPase Cdc42p
Singularity in budding: A role for the evolutionarily conserved small GTPase Cdc42p
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DOI：
10.1073/pnas.182370299
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发表时间：
2002-09-17
影响因子：
11.1
通讯作者：
Bi, E
中科院分区：
文献类型：
--
作者：
Caviston, JP;Tcheperegine, SE;Bi, E
芽殖酵母酿酒酵母在细胞周期的特定时间和细胞表面的特定位置启动极化生长或芽殖，每个细胞周期一次。关于时空调控机制的分子本质知之甚少。目前还不清楚，在形成芽所需的众多蛋白质中，哪些因素（如果有的话）参与了决定出芽频率的决定。在这里，我们描述了一类cdc42突变体，在一个核周期内在细胞表面的随机位置产生多个芽。负责该表型的关键突变影响氨基酸残基60，其位于GTIP结合和水解所需的结构域中。这种突变绕过了必需的鸟嘌呤核苷酸交换因子Cdc24p的要求，表明残基60的改变使Cdc42p过度活跃，这是生物化学证实的。这一结果也表明Cdc24 p的唯一基本功能是激活Cdc42 p。总之，这些数据表明，极化生长的时间和空间调节收敛在Cdc42p的水平，Cdc42p的活性决定了出芽频率。
The budding yeast Saccharomyces cerevisiae initiates polarized growth or budding once per cell cycle at a specific time of the cell cycle and at a specific location on the cell surface. Little is known about the molecular nature of the temporal and spatial regulatory mechanisms. It is also unclear what factors, if any, among the numerous proteins required to make a bud are involved in the determination of budding frequency. Here we describe a class of cdc42 mutants that produce multiple buds at random locations on the cell surface within one nuclear cycle. The critical mutation responsible for this phenotype affects amino acid residue 60, which is located in a domain required for GTIP binding and hydrolysis. This mutation bypasses the requirement for the essential guanine-nucleotide-exchange factor Cdc24p, suggesting that the alteration at residue 60 makes Cdc42p hyperactive, which was confirmed biochemically. This result also suggests that the only essential function of Cdc24p is to activate Cdc42p. Together, these data suggest that the temporal and spatial regulation of polarized growth converges at the level of Cdc42p and that the activity of Cdc42p determines the budding frequency.