GTPase-activating proteins for Cdc42
GTPase-activating proteins for Cdc42
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DOI：
10.1128/ec.1.3.469-480.2002
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发表时间：
2002-06-01
期刊：
影响因子：
--
通讯作者：
Sprague, GF
中科院分区：
文献类型：
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作者：
Smith, GR;Givan, SA;Sprague, GF
Rho型GTdR，Cdc42，在酵母生命周期中有多种功能，包括胞质分裂的septin组织，信息素反应和单倍体侵入性生长。一组称为GTP酶激活蛋白（GAP）的蛋白质催化GTP水解为GDP，从而使Cdc42失活。在这项研究开始时，Cdc42有一个已知的GAP Bem 3和一个推定的GAP Rga 1。我们鉴定了Cdc42的另一个推定的GAP，并将其命名为Rga2（Rho GTP酶激活蛋白2）。我们证实了遗传和生化标准，Rga1，Rga2和Bem 3作为间隙Cdc42。Rga 1，Rga 2和Bem 3的详细表征表明它们调节Cdc42功能的不同子集。特别是，个别GAP的缺失赋予不同的表型。例如，RGA1的缺失，而不是RGA2或BEM3的缺失，导致了过度侵袭性生长。此外，Rga 1和Rga 2的过量产生或丢失，但Bem 3不影响Cdc42与Ste20的双杂交相互作用，Ste20是单倍体侵入性生长所需的p21激活激酶（PAK）激酶。这些结果表明，Rga 1，可能Rga 2，促进Cdc42与Ste20的相互作用，介导信号在单倍体侵入性生长途径。BEM3的缺失导致细胞具有在rga1 Delta或rga2 Delta菌株中未观察到的严重形态缺陷。这些数据表明，Bem 3，并在较小程度上，Rga 1和Rga 2促进Cdc42在septin组织中的作用。因此，GAP似乎在调节Cdc42功能的特定方面发挥作用。或者，不同的表型可能反映了突变株中GAP活性的定量差异而不是定性差异。
The Rho-type GTPase, Cdc42, has been implicated in a variety of functions in the yeast life cycle, including septin organization for cytokinesis, pheromone response, and haploid invasive growth. A group of proteins called GTPase-activating proteins (GAPs) catalyze the hydrolysis of GTP to GDP, thereby inactivating Cdc42. At the time this study began, there was one known GAP, Bem3, and one putative GAP, Rga1, for Cdc42. We identified another putative GAP for Cdc42 and named it Rga2 (Rho GTPase-activating protein 2). We confirmed by genetic and biochemical criteria that Rga1, Rga2, and Bem3 act as GAPs for Cdc42. A detailed characterization of Rga1, Rga2, and Bem3 suggested that they regulate different subsets of Cdc42 function. In particular, deletion of the individual GAPs conferred different phenotypes. For example, deletion of RGA1, but not RGA2 or BEM3, caused hyperinvasive growth. Furthermore, overproduction or loss of Rga1 and Rga2, but not Bem3, affected the two-hybrid interaction of Cdc42 with Ste20, a p21-activated kinase (PAK) kinase required for haploid invasive growth. These results suggest Rga1, and possibly Rga2, facilitate the interaction of Cdc42 with Ste20 to mediate signaling in the haploid invasive growth pathway. Deletion of BEM3 resulted in cells with severe morphological defects not observed in rga1Delta or rga2Delta strains. These data suggest that Bem3 and, to a lesser extent, Rga1 and Rga2 facilitate the role of Cdc42 in septin organization. Thus, it appears that the GAPs play a role in modulating specific aspects of Cdc42 function. Alternatively, the different phenotypes could reflect quantitative rather than qualitative differences in GAP activity in the mutant strains.