Gpa2p, a G-protein alpha-subunit, regulates growth and pseudohyphal development in Saccharomyces cerevisiae via a cAMP-dependent mechanism
Gpa2p, a G-protein alpha-subunit, regulates growth and pseudohyphal development in Saccharomyces cerevisiae via a cAMP-dependent mechanism
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DOI：
10.1074/jbc.272.33.20321
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发表时间：
1997-08-15
影响因子：
4.8
通讯作者：
Lisanti, MP
中科院分区：
文献类型：
--
作者：
Kubler, E;Mosch, HU;Lisanti, MP
小GTP结合蛋白Ras和异源三聚体G蛋白是真核细胞生长和发育的关键调节因子。在哺乳动物细胞中，Ras的功能是响应生长因子调节促分裂原活化蛋白激酶途径，而许多异源三聚体GTP结合蛋白α亚基通过腺苷酸环化酶调节cAMP水平，这是激素作用的结果。相反，在酿酒酵母中，Ras 1和Ras 2蛋白调节腺苷酸环化酶。两个酵母G蛋白α亚基（GPA 1和GPA 2），只有GPA 1已被很好地研究，并显示出负调控有丝分裂原活化蛋白激酶途径后，信息素刺激，在这份报告中，我们表明，删除GPA 2基因编码的其他酵母G蛋白α亚基导致缺陷，在假菌丝的发展，此外，在Ras 2 p缺失的情况下，GPA 2基因对于正常生长是不可缺少的。这两种表型都可以通过PDE 2基因产物的缺失来挽救，其通过切割使cAMP失活，这表明这些表型可以归因于细胞内cAMP的低水平。为支持这一观点，在生长培养基中加入外源cAMP也足以拯救GPA 2缺失菌株的表型。综上所述，我们的结果直接证明了G蛋白α亚基可以调节S.通过cAMP依赖性机制，在这些酵母GPA 2缺失菌株中哺乳动物G蛋白α-亚基的异源表达可以为在体内无效设置中哺乳动物G蛋白功能的突变分析提供有价值的工具。
The small GTP-binding protein Ras and heterotrimeric G-proteins are key regulators of growth and development in eukaryotic cells. In mammalian cells, Ras functions to regulate the mitogen-activated protein kinase pathway in response to growth factors, whereas many heterotrimeric GTP-binding protein alpha-subunits modulate cAMP levels through adenylyl cyclase as a consequence of hormonal action. In contrast, in the yeast Saccharomyces cerevisiae, it is the Ras1 and Ras2 proteins that regulate adenylyl cyclase. Of the two yeast G-protein alpha-subunits (GPA1 and GPA2), only GPA1 has been well studied and shown to negatively regulate the mitogen-activated protein kinase pathway upon pheromone stimulation,In this report, we show that deletion of the GPA2 gene encoding the other yeast G-protein alpha-subunit leads to a defect in pseudohyphal development, Also, the GPA2 gene is indispensable for normal growth in the absence of Ras2p. Both of these phenotypes can be rescued by deletion of the PDE2 gene product, which inactivates cAMP by cleavage, suggesting that these phenotypes can be attributed to low levels of intracellular cAMP. In support of this notion, addition of exogenous cAMP to the growth media was also sufficient to rescue the phenotype of a GPA2 deletion strain, Taken together, our results directly demonstrate that a G-protein alpha-subunit can regulate the growth and pseudohyphal development of S. cerevisiae via a cAMP-dependent mechanism, Heterologous expression of mammalian G-protein alpha-subunits in these yeast GPA2 deletion strains could provide a valuable tool for the mutational analysis of mammalian G-protein function in an in vivo null setting.