斜卧青霉转录调控因子BglR的缺失对纤维素酶生产的影响

Effects of a novel transcription factor BglR from Penicillium decumbens on cellulase production

摘要:

【目的】斜卧青霉(Penicillium decumbens)作为高效分泌纤维素酶的重要丝状真菌, 其纤维素酶的合成与分泌在转录水平上被调控。进一步研究纤维素酶基因表达的转录调控, 构建高效高产纤维素酶的工业菌株。【方法】根据斜卧青霉114-2在不同碳源生长条件下基因组表达谱的差异, 发现新的转录调控因子BglR (PDE-01706), 该蛋白与产黄青霉(Penicillium chrysogenum) Pc20g04780的锌指结构蛋白具有59%同源性。通过基因同源双交换, 得到BglR缺失突变株ΔbglR-1, 对突变株ΔbglR-1的表型、营养生长、产纤维素酶活、蛋白分泌能力及发酵液pH变化进行研究。【结果】转录调控因子BglR的缺失可导致突变株ΔbglR-1的β-葡萄糖苷酶活力提高40%, 并造成其滤纸酶活、内切葡聚糖酶及木聚糖酶活明显降低。【结论】结果表明转录调控因子BglR对于斜卧青霉纤维素酶的调控有重要作用。

Abstract:

[Objective] Penicillium decumbens is an important filamentous fungus that efficiently secrets cellulases. The biosynthesis and secretion of these cellulases are regulated on transcription levels. In order to further study the mechanism of transcriptional regulation of cellulases encoding genes and construct industrial strains with high cellulases production, [Methods] We identified a transcription regulator BglR (PDE-01706) from P. decumbens 114-2 by comparing gene expression profiles under different carbon sources condition. This transcription regulator shares a 59% sequence identity with the zinc finger protein Pc20g04780 from Penicillium chrysogenum. P. decumbens ΔbglR-1 knockout strain was constructed with homologous double crossover recombination. The phenotype of this strain was investigated, including its hyphal growth, protein secretion level, cellulase secretion level and extracellular pH level. [Results] It was shown that the deletion of the transcription factor BglR in P. decumbens ΔbglR-1 leads to an increase of extracellular β-glucosidase activity by 40%, and a lowered filter paper activity, endoglucanases and xylanase level. [Conclusion] From these results it is proposed that BglR plays a major role in the regulation of cellulase production of P. decumbens.