Biomass Energy Center for Arid and Semi-Arid Lands, Northwest A&F University, Yangling, People's Republic of China.
College of Life Sciences, Northwest A&F University, Yangling, People's Republic of China.
Appl Environ Microbiol. 2020 Jul 20;86(15). doi: 10.1128/AEM.00653-20.
Filamentous fungi are intensively used for producing industrial enzymes, including lignocellulases. Employing insoluble cellulose to induce the production of lignocellulases causes some drawbacks, e.g., a complex fermentation operation, which can be overcome by using soluble inducers such as cellobiose. Here, a triple β-glucosidase mutant of , which prevents rapid turnover of cellobiose and thus allows the disaccharide to induce lignocellulases, was applied to profile the proteome responses to cellobiose and cellulose (Avicel). Our results revealed a shared proteomic response to cellobiose and Avicel, whose elements included lignocellulases and cellulolytic product transporters. While the cellulolytic proteins showed a correlated increase in protein and mRNA levels, only a moderate correlation was observed on a proteomic scale between protein and mRNA levels ( = 0.31). Ribosome biogenesis and rRNA processing were significantly overrepresented in the protein set with increased protein but unchanged mRNA abundances in response to Avicel. Ribosome biogenesis, as well as protein processing and protein export, was also enriched in the protein set that showed increased abundance in response to cellobiose. NCU05895, a homolog of yeast CWH43, is potentially involved in transferring a glycosylphosphatidylinositol (GPI) anchor to nascent proteins. This protein showed increased abundance but no significant change in mRNA levels. Disruption of CWH43 resulted in a significant decrease in cellulase activities and secreted protein levels in cultures grown on Avicel, suggesting a positive regulatory role for CWH43 in cellulase production. The findings should have an impact on a systems engineering approach for strain improvement for the production of lignocellulases. Lignocellulases are important industrial enzymes for sustainable production of biofuels and bio-products. Insoluble cellulose has been commonly used to induce the production of lignocellulases in filamentous fungi, which causes a difficult fermentation operation and enzyme loss due to adsorption to cellulose. The disadvantages can be overcome by using soluble inducers, such as the disaccharide cellobiose. Quantitative proteome profiling of the model filamentous fungus revealed cellobiose-dependent pathways for cellulase production, including protein processing and export. A protein (CWH43) potentially involved in protein processing was found to be a positive regulator of lignocellulase production. The cellobiose-dependent mechanisms provide new opportunities to improve the production of lignocellulases in filamentous fungi.
丝状真菌被广泛用于生产工业酶,包括木聚糖酶。使用不溶性纤维素诱导木聚糖酶的产生会导致一些缺点,例如复杂的发酵操作,这可以通过使用可溶性诱导物如纤维二糖来克服。在这里,我们应用一种三重β-葡萄糖苷酶突变体(),该突变体阻止纤维二糖的快速周转,从而使二糖能够诱导木聚糖酶的产生,来分析纤维二糖和纤维素(Avicel)对蛋白质组的响应。我们的结果揭示了对纤维二糖和 Avicel 的共同蛋白质组响应,其元素包括木聚糖酶和纤维素酶产物转运蛋白。虽然纤维素酶蛋白的蛋白质和 mRNA 水平呈相关增加,但在蛋白质组水平上仅观察到蛋白质和 mRNA 水平之间的中度相关性(=0.31)。核糖体生物发生和 rRNA 加工在响应 Avicel 时蛋白质水平增加但 mRNA 丰度不变的蛋白质组中显著过表达。核糖体生物发生以及蛋白质加工和蛋白质输出也在响应纤维二糖时蛋白质丰度增加的蛋白质组中富集。NCU05895 是酵母 CWH43 的同源物,可能参与将糖基磷脂酰肌醇(GPI)锚定到新生蛋白上。该蛋白的丰度增加,但 mRNA 水平没有显著变化。在 Avicel 上培养时,CWH43 的缺失导致纤维素酶活性和分泌蛋白水平显著降低,表明 CWH43 在纤维素酶产生中具有正调控作用。这些发现应该对用于生产木聚糖酶的菌株改良的系统工程方法产生影响。木聚糖酶是可持续生产生物燃料和生物制品的重要工业酶。在丝状真菌中,通常使用不溶性纤维素来诱导木聚糖酶的产生,这会导致困难的发酵操作和由于吸附到纤维素而导致的酶损失。可以通过使用可溶性诱导物,如二糖纤维二糖来克服这些缺点。对模式丝状真菌的定量蛋白质组分析揭示了纤维二糖依赖的纤维素酶产生途径,包括蛋白质加工和输出。发现一种可能参与蛋白质加工的蛋白(CWH43)是木聚糖酶产生的正调控因子。纤维二糖依赖的机制为提高丝状真菌中木聚糖酶的生产提供了新的机会。