The heterotrimeric G-protein GanB(α)-SfaD(β)-GpgA(γ) is a carbon source sensor involved in early cAMP-dependent germination in Aspergillus nidulans
The heterotrimeric G-protein GanB(α)-SfaD(β)-GpgA(γ) is a carbon source sensor involved in early cAMP-dependent germination in Aspergillus nidulans
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DOI：
10.1534/genetics.105.040584
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发表时间：
2005-09-01
期刊：
影响因子：
3.3
通讯作者：
d'Enfert, C
中科院分区：
文献类型：
--
作者：
Lafon, A;Seo, JA;d'Enfert, C
异源三聚体G蛋白在丝状子囊菌构巢曲霉中cAMP依赖的分生孢子萌发中的作用进行了研究。我们表明，G α亚基GanB介导的快速和短暂的激活cAMP合成响应于葡萄糖在萌发的早期。此外，单个G蛋白亚基的缺失导致缺陷的海藻糖动员和改变的萌发动力学，表明GanB（alpha）-SfaD（beta）-GpgA（gamma）构成功能性异源三聚体并控制响应于葡萄糖的cAMP/PKA信号传导以及分生孢子萌发。进一步的遗传分析表明，GanB在cAMP/PKA信号传导中起主要作用，而SfaD-GpgA（G β-γ）异二聚体对于葡萄糖敏化的GanB信号传导的适当激活至关重要。此外，RGS蛋白RgsA还通过减弱GanB信号传导参与cAMP/PKA途径和萌发的调节。遗传上位性分析使我们得出结论，GanB（α）-SfaD（β）-GpgA（γ）对分生孢子萌发的所有控制都是通过cAMP/PKA途径介导的。此外，GanB可能在感知各种碳源和随后激活下游信号以用于萌发中起作用。
The role of heterotrimeric G-proteins in cAMP-dependent germination of conidia was investigated in the filamentous ascomycete Aspergillus nidulans. We demonstrate that the G alpha-subunit GanB mediates a rapid and transient activation of cAMP synthesis in response to glucose during the early period of germination. Moreover, deletion of individual G-protein subunits resulted in defective trehalose mobilization and altered germination kinetics, indicating that GanB(alpha)-SfaD(beta)-GpgA(gamma) constitutes a functional heterotrimer and controls cAMP/PKA signaling in response to glucose as well as conidial germination. Further genetic analyses suggest that GanB plays a primary role in cAMP/PKA signaling, whereas the SfaD-GpgA (G beta-gamma) heterodimer is crucial for proper activation of GanB signaling sensitized by glucose. In addition, the RGS protein RgsA is also involved in regulation of the cAMP/PKA pathway and germination via attenuation of GanB signaling. Genetic epistatic analyses led us to conclude that all controls exerted by GanB(alpha)-SfaD(beta)-GpgA(gamma) on conidial germination are mediated through the cAMP/PKA pathway. Furthermore, GanB may function in sensing various carbon sources and subsequent activation of downstream signaling for germination.