College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei Province, PR China.
Fungal Biol. 2012 Feb;116(2):225-33. doi: 10.1016/j.funbio.2011.11.005. Epub 2011 Nov 20.
FlbA (fluffy low brlA expression), a regulator of the G protein signalling (RGS) pathway, has been implicated in the control of hyphal development, sporulation, mycotoxin/pigment production in many kinds of filamentous fungi and yeasts. In the current study, a FlbA-like protein gene mrflbA (Monascus ruber flbA) was isolated, sequenced, and disrupted in order to investigate the RGS function in M. ruber. The results revealed that the derived protein of the mrflbA gene consisted of 734 amino acids and had the conserved RGS domain at the C-terminus and two DEP (dishevelled, Egl-10, pleckstrin) domains at the N-terminus similar to the structure of RGS proteins in other filamentous fungi. Deletion of the mrflbA gene resulted in the formation of an abnormal colony phenotype with fluffy aerial hyphae that autolyzed as the colony grew on potato dextrose agar (PDA) at 28°C. Additionally, mrflbA deletion could repress conidial germination and pigment/citrinin production in M. ruber M-7. Real-time RT-PCR analysis demonstrated that the transcription level of the G protein α subunit (Gα) was remarkably increased in the mrflbA deletion strain. These results suggest that mrflbA is involved in the modulation of aerial hyphal development and secondary metabolism, as well as, negative regulation of Gα subunit expression in M. ruber M-7.
FlbA（绒毛状低 brlA 表达）是 G 蛋白信号转导（RGS）途径的调节剂，它参与控制丝状真菌和酵母中的菌丝发育、孢子形成、真菌毒素/色素的产生。在本研究中，分离、测序并敲除了 FlbA 样蛋白基因 mrflbA（红曲霉 FlbA），以研究 RGS 在红曲霉中的功能。结果表明，mrflbA 基因的推导蛋白由 734 个氨基酸组成，在 C 端具有保守的 RGS 结构域，在 N 端具有两个 DEP（dsh、Egl-10、pleckstrin）结构域，类似于其他丝状真菌中 RGS 蛋白的结构。mrflbA 基因的缺失导致异常菌落表型的形成，具有绒毛状气生菌丝，随着菌落在 28°C 的马铃薯葡萄糖琼脂（PDA）上生长，气生菌丝自溶。此外，mrflbA 缺失可以抑制红曲霉 M-7 中的分生孢子萌发和色素/桔霉素的产生。实时 RT-PCR 分析表明，mrflbA 缺失菌株中 G 蛋白α亚基（Gα）的转录水平显著增加。这些结果表明，mrflbA 参与调节红曲霉 M-7 中的气生菌丝发育和次级代谢，以及 Gα 亚基表达的负调控。
