Regulators of G-protein signalling in Aspergillus nidulans:: RgsA downregulates stress response and stimulates asexual sporulation through attenuation of GanB (Gα) signalling
Regulators of G-protein signalling in Aspergillus nidulans:: RgsA downregulates stress response and stimulates asexual sporulation through attenuation of GanB (Gα) signalling
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DOI：
10.1111/j.1365-2958.2004.04163.x
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发表时间：
2004-07-01
影响因子：
3.6
通讯作者：
Yu, JH
中科院分区：
文献类型：
--
作者：
Han, KH;Seo, JA;Yu, JH
G蛋白信号调节因子在控制异源三聚体G蛋白信号的程度方面起着至关重要的作用。除了之前研究过的flbA之外，我们在构巢曲霉的基因组中鉴定出了三个编码假定的RGS蛋白的基因（rgsA、rgsB和rgsC）。对rgsA基因的特性研究表明，RgsA下调色素产生和分生孢子萌发，但刺激无性孢子形成（产孢）。rgsA的缺失（ΔrgsA）导致菌落变小，气生菌丝增多，棕色色素积累增加，以及分生孢子和营养菌丝对氧化和热应激的耐受性增强。此外，ΔrgsA导致在无碳源的情况下分生孢子萌发。flbA和rgsA两者的缺失导致一种累加表型，这表明由FlbA和RgsA控制的G蛋白途径是不同的。由ΔrgsA引起的形态和代谢改变因编码Gα亚基的ganB的缺失而被抑制，这表明RgsA的主要作用是负向控制GanB介导的信号传导。rgsA的过表达导致在液体浸没培养中不适当的产孢，支持了GanB信号传导抑制产孢这一观点。我们的研究结果在构巢曲霉中确定了第二对特定的RGS - Gα组合，它可能控制真菌细胞对环境变化的上游调节。
Regulators of G-protein signalling play a crucial role in controlling the degree of heterotrimeric G-protein signalling. In addition to the previously studied flbA, we have identified three genes (rgsA, rgsB and rgsC) encoding putative RGS proteins in the genome of Aspergillus nidulans. Characterization of the rgsA gene revealed that RgsA downregulates pigment production and conidial germination, but stimulates asexual sporulation (conidiation). Deletion of rgsA (DeltargsA) resulted in reduced colony size with increased aerial hyphae, elevated accumulation of brown pigments as well as enhanced tolerance of conidia and vegetative hyphae against oxidative and thermal stress. Moreover, DeltargsA resulted in conidial germination in the absence of a carbon source. Deletion of both flbA and rgsA resulted in an additive phenotype, suggesting that the G-protein pathways controlled by FlbA and RgsA are different. Morphological and metabolic alterations caused by DeltargsA were suppressed by deletion of ganB encoding a Galpha subunit, indicating that the primary role of RgsA is to control negatively GanB-mediated signalling. Overexpression of rgsA caused inappropriate conidiation in liquid submerged culture, supporting the idea that GanB signalling represses conidiation. Our findings define a second and specific RGS-Galpha pair in A. nidulans, which may govern upstream regulation of fungal cellular responses to environmental changes.