Department of Microbiology and Biotechnology, Daejeon University, Daejon, Republic of Korea.
Curr Genet. 2009 Dec;55(6):631-41. doi: 10.1007/s00294-009-0276-4. Epub 2009 Nov 14.
The roles of the Gbetagamma subunits of the opportunistic human pathogen Aspergillus fumigatus were investigated. The predicted AfuSfaD (Gbeta) protein consists of 353 amino acids and shows 94-98% similarity with other Aspergillus Gbeta subunits. AfuGpgA consists of 90 amino acids showing 95-98% identity with other fungal G-protein gamma subunits. The deletion (Delta) of AfusfaD or AfugpgA resulted in severe impairment in vegetative growth, conidial germination and conidial trehalose breakdown. While the total number of conidia produced by DeltaAfusfaD and DeltaAfugpgA strains on solid medium was only about 1% of wild type, the growth-adjusted conidiation levels were twofold higher than those of wild type. Enhanced formation of conidiophores and elevated AfubrlA mRNA levels were observable in DeltaAfusfaD or DeltaAfugpgA strains in liquid submerged culture. Moreover, overexpression of AfusfaD or AfugpgA caused reduced levels of submerged culture conidiation, indicating that Gbetagamma is involved in negative regulation of conidiation. Gliotoxin and other metabolites were not detected in the chloroform extracts of DeltaAfusfaD and DeltaAfugpgA culture filtrates. Northern blot analyses revealed that, while AfulaeA mRNA levels unchanged, accumulation of gliZ mRNA was delayed by DeltaAfusfaD or DeltaAfugpgA. A model summarizing the roles of AfusfaD and AfugpgA in A. fumigatus is presented.
本研究调查了机会性病原体烟曲霉中 Gbetagamma 亚基的作用。预测的 AfuSfaD（Gbeta）蛋白由 353 个氨基酸组成，与其他曲霉 Gbeta 亚基具有 94-98%的相似性。AfuGpgA 由 90 个氨基酸组成，与其他真菌 G 蛋白γ亚基具有 95-98%的同一性。AfuSfaD 或 AfuGpgA 的缺失导致营养生长、分生孢子萌发和分生孢子海藻糖分解严重受损。虽然 DeltaAfusfaD 和 DeltaAfugpgA 菌株在固体培养基上产生的分生孢子总数仅约为野生型的 1%，但经过生长调整的产孢水平比野生型高出两倍。在液体深层培养中，DeltaAfusfaD 或 DeltaAfugpgA 菌株中可观察到分生孢子梗的形成增强，并且 AfubrlA mRNA 水平升高。此外，过表达 AfusfaD 或 AfugpgA 导致深层培养产孢水平降低，表明 Gbetagamma 参与了分生孢子形成的负调控。在 DeltaAfusfaD 和 DeltaAfugpgA 培养滤液的氯仿提取物中未检测到蕈毒碱和其他代谢物。Northern blot 分析表明，虽然 AfulaeA mRNA 水平不变，但 DeltaAfusfaD 或 DeltaAfugpgA 延迟了 gliZ mRNA 的积累。本文提出了一个总结 AfuSfaD 和 AfuGpgA 在烟曲霉中作用的模型。
