Mutation of RGA1, which encodes a putative GTPase-activating protein for the polarity-establishment protein Cdc42p, activates the pheromone-response pathway in the yeast Saccharomyces cerevisiae.
Mutation of RGA1, which encodes a putative GTPase-activating protein for the polarity-establishment protein Cdc42p, activates the pheromone-response pathway in the yeast Saccharomyces cerevisiae.
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RGA1 编码极性建立蛋白 Cdc42p 的推定 GTP 酶激活蛋白，其突变可激活酿酒酵母中的信息素响应途径。
DOI：
10.1101/gad.9.23.2949
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发表时间：
1995
影响因子：
10.5
通讯作者：
SpragueJr,GF
中科院分区：
文献类型：
--
作者：
Stevenson,BJ;Ferguson,B;DeVirgilio,C;Bi,E;Pringle,JR;Ammerer,G;SpragueJr,GF
我们选择了在缺乏三聚体G蛋白的β亚基的情况下表现出结构性活性信息素反应途径的酵母突变株。对其中一个突变体的遗传分析表明，它在两个不同的基因中包含隐性突变，这两个基因都对构成表型有贡献。一个突变识别RGA1基因座(Rho GTPase激活蛋白)，它编码一种与GAP结构域和LIM结构域同源的蛋白质。在缺乏Gβ亚基的菌株中，RGA1的缺失足以激活该途径。此外，在野生型菌株中，RGA1的缺失增加了信息素途径中的信号传递，而RGA1的过度表达抑制了信号传递，表明RGa1p作为信息素反应途径的负调节因子发挥作用。原始突变体中存在的第二个突变被证明是一个已知基因PBS2的等位基因，该基因编码一种可能在高渗透压应激途径中发挥作用的蛋白激酶。PBS2突变增强了rga1突变的表型，但本身并不激活信息素途径。遗传分析和双杂交分析表明，Rga1p的一个重要靶标是cdc42p，它是一种p21GTP酶，在极性建立和出芽过程中是必需的。这一发现，再加上最近对哺乳动物和酵母细胞的实验表明，CDC42p可以与在信息素途径中工作的蛋白激酶Ste20p相互作用并激活，这使得我们认为Rga1p控制CDc42p的活性，而后者又通过Ste20p控制信息素途径中的信号幅度。
We have selected yeast mutants that exhibit a constitutively active pheromone-response pathway in the absence of the beta subunit of the trimeric G protein. Genetic analysis of one such mutant revealed that it contained recessive mutations in two distinct genes, both of which contributed to the constitutive phenotype. One mutation identifies the RGA1 locus (Rho GTPase activating protein), which encodes a protein with homology to GAP domains and to LIM domains. Deletion of RGA1 is sufficient to activate the pathway in strains lacking the G beta subunit. Moreover, in wild-type strains, deletion of RGA1 increases signaling in the pheromone pathway, whereas over-expression of RGA1 dampens signaling, demonstrating that Rga1p functions as a negative regulator of the pheromone response pathway. The second mutation present in the original mutant proved to be an allele of a known gene, PBS2, which encodes a putative protein kinase that functions in the high osmolarity stress pathway. The pbs2 mutation enhanced the rga1 mutant phenotype, but by itself did not activate the pheromone pathway. Genetic and two-hybrid analyses indicate that an important target of Rga1p is Cdc42p, a p21 GTPase required for polarity establishment and bud emergence. This finding coupled with recent experiments with mammalian and yeast cells indicating that Cdc42p can interact with and activate Ste20p, a protein kinase that operates in the pheromone pathway, leads us to suggest that Rga1p controls the activity of Cdc42p, which in turn controls the magnitude of signaling in the pheromone pathway via Ste20p.