Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, No.12 Zhongguancun South St., Haidian District, Beijing 100081, China.
Beijing Key Lab of Plant Resource Research and Development, Beijing Technology and Business University, No.11 Fucheng Road, Haidian District, Beijing 100048, China.
Int J Mol Sci. 2019 Jul 28;20(15):3693. doi: 10.3390/ijms20153693.
The thermophilic fungus produces cellulolytic enzymes that are of great scientific and commercial interest; however, few reports have focused on its cellulase expression regulation mechanism. In this study, we constructed a gene (carbon catabolite repressor gene) disruption mutant strain of that exhibited a reduced radial growth rate and stouter hyphae compared to the wild-type (WT) strain. The disruption mutant also expressed elevated pNPCase (cellobiohydrolase activities), pNPGase (β-glucosidase activities), and xylanase levels in non-inducing fermentation with glucose. Unlike other fungi, the disruption mutant displayed lower FPase (filter paper activity), CMCase (carboxymethyl cellulose activity), pNPCase, and pNPGase activity than observed in the WT strain when fermentation was induced using Avicel, whereas its xylanase activity was higher than that of the parental strain. These results indicate that CreA acts as a crucial regulator of hyphal growth and is part of a unique cellulase expression regulation mechanism in . These findings provide a new perspective to improve the understanding of carbon catabolite repression regulation mechanisms in cellulase expression, and enrich the knowledge of metabolism diversity and molecular regulation of carbon metabolism in thermophilic fungi.
嗜热真菌产生的纤维素酶具有重要的科学和商业价值；然而，关于其纤维素酶表达调控机制的研究较少。本研究构建了一株 基因（碳源分解代谢物阻遏物基因）敲除突变株，与野生型（WT）菌株相比，该突变株的径向生长速率降低，菌丝较粗。该敲除突变株在以葡萄糖为非诱导发酵时，表达更高水平的 pNPCase（纤维二糖水解酶活性）、pNPGase（β-葡萄糖苷酶活性）和木聚糖酶。与其他真菌不同，当用 Avicel 诱导发酵时，与野生型菌株相比， 敲除突变株的 FPase（滤纸活性）、CMCase（羧甲基纤维素酶活性）、pNPCase 和 pNPGase 活性较低，但其木聚糖酶活性高于亲本菌株。这些结果表明 CreA 作为菌丝生长的关键调控因子，参与了 中独特的纤维素酶表达调控机制。这些发现为深入了解纤维素酶表达中的碳源分解代谢物阻遏调控机制提供了新的视角，并丰富了嗜热真菌碳代谢多样性和分子调控的知识。
