Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands.
Sci Rep. 2017 Sep 27;7(1):12356. doi: 10.1038/s41598-017-12362-y.
Aspergillus niger produces an arsenal of extracellular enzymes that allow synergistic degradation of plant biomass found in its environment. Pectin is a heteropolymer abundantly present in the primary cell wall of plants. The complex structure of pectin requires multiple enzymes to act together. Production of pectinolytic enzymes in A. niger is highly regulated, which allows flexible and efficient capture of nutrients. So far, three transcriptional activators have been linked to regulation of pectin degradation in A. niger. The L-rhamnose-responsive regulator RhaR controls the production of enzymes that degrade rhamnogalacturonan-I. The L-arabinose-responsive regulator AraR controls the production of enzymes that decompose the arabinan and arabinogalactan side chains of rhamnogalacturonan-II. The D-galacturonic acid-responsive regulator GaaR controls the production of enzymes that act on the polygalacturonic acid backbone of pectin. This project aims to better understand how RhaR, AraR and GaaR co-regulate pectin degradation. For that reason, we constructed single, double and triple disruptant strains of these regulators and analyzed their growth phenotype and pectinolytic gene expression in A. niger grown on sugar beet pectin.
黑曲霉产生了一系列细胞外酶，这些酶允许协同降解其环境中发现的植物生物质。果胶是一种大量存在于植物初生细胞壁中的杂多糖。果胶的复杂结构需要多种酶共同作用。黑曲霉中原果胶酶的产生受到高度调控，这使得其能够灵活高效地捕获营养物质。迄今为止，已有三种转录激活因子与黑曲霉中原果胶降解的调控有关。L-鼠李糖响应调节剂 RhaR 控制降解鼠李半乳糖醛酸聚糖 I 的酶的产生。L-阿拉伯糖响应调节剂 AraR 控制分解鼠李半乳糖醛酸聚糖 II 阿拉伯聚糖和阿拉伯半乳聚糖侧链的酶的产生。D-半乳糖醛酸响应调节剂 GaaR 控制作用于果胶聚半乳糖醛酸主链的酶的产生。本项目旨在更好地了解 RhaR、AraR 和 GaaR 如何共同调控果胶的降解。为此，我们构建了这些调节剂的单、双和三重缺失株，并在糖用甜菜果胶上生长的黑曲霉中分析了它们的生长表型和原果胶酶基因表达。
