Fungal Biotechnology in Wood Science, Holzforschung München, TUM School of Life Sciences, Technical University of Munich, Freising, Germany.
Faculty of Science, Suez Canal University, Ismailia, Egypt.
Appl Microbiol Biotechnol. 2024 Dec;108(1):83. doi: 10.1007/s00253-023-12907-4. Epub 2024 Jan 8.
Filamentous fungi like Neurospora crassa are able to take up and metabolize important sugars present, for example, in agricultural and human food wastes. However, only a fraction of all putative sugar transporters in filamentous fungi has been characterized to date, and for many sugar substrates, the corresponding transporters are unknown. In N. crassa, only 14 out of the 42 putative major facilitator superfamily (MFS)-type sugar transporters have been characterized so far. To uncover this hidden potential for biotechnology, it is therefore necessary to find new strategies. By correlation of the uptake profile of sugars of interest after different induction conditions with the expression profiles of all 44 genes encoding predicted sugar transporters in N. crassa, together with an exhaustive phylogenetic analysis using sequences of characterized fungal sugar transporters, we aimed to identify transporter candidates for the tested sugars. Following this approach, we found a high correlation of uptake rates and expression strengths for many sugars with dedicated transporters, like galacturonic acid and arabinose, while the correlation is loose for sugars that are transported by several transporters due to functional redundancy. Nevertheless, this combinatorial approach allowed us to elucidate the uptake system for the disaccharide lactose, a by-product of the dairy industry, which consists of the two main cellodextrin transporters CDT-1 and CDT-2 with a minor contribution of the related transporter NCU00809. Moreover, a non-MFS transporter involved in glycerol transport was also identified. Deorphanization of sugar transporters or identification of transporters for orphan sugar substrates by correlation of uptake kinetics with transporter expression and phylogenetic information can thus provide a way to optimize the reuse of food industry by-products and agricultural wastes by filamentous fungi in order to create economic value and reduce their environmental impact. KEY POINTS: • The Neurospora crassa genome contains 30 uncharacterized putative sugar transporter genes. • Correlation of transporter expression and sugar uptake profiles can help to identify transporters for orphan sugar substrates. • CDT-1, CDT-2, and NCU00809 are key players in the transport of the dairy by-product lactose in N. crassa.
丝状真菌，如粗糙脉孢菌，能够摄取和代谢重要的糖，例如农业和人类食物废物中的糖。然而，迄今为止，丝状真菌中只有一部分假定的糖转运蛋白得到了描述，对于许多糖底物，相应的转运蛋白仍然未知。在粗糙脉孢菌中，到目前为止，仅对 42 个假定的主要易化因子超家族（MFS）型糖转运蛋白中的 14 个进行了描述。为了挖掘这种生物技术的隐藏潜力，因此有必要寻找新的策略。我们通过将不同诱导条件下感兴趣的糖的摄取情况与粗糙脉孢菌中 44 个编码预测糖转运蛋白的基因的表达谱进行相关分析，并使用已描述的真菌糖转运蛋白的序列进行详尽的系统发育分析，旨在鉴定测试糖的转运蛋白候选物。通过这种方法，我们发现许多糖的摄取速率和表达强度与专用转运蛋白高度相关，例如半乳糖醛酸和阿拉伯糖，而由于功能冗余，由几种转运蛋白运输的糖的相关性则较为松散。尽管如此，这种组合方法使我们能够阐明乳制品工业副产物二糖乳糖的摄取系统，该系统由两个主要的纤维二糖转运蛋白 CDT-1 和 CDT-2 组成，其次是相关转运蛋白 NCU00809。此外，还鉴定了参与甘油运输的非 MFS 转运蛋白。通过将摄取动力学与转运蛋白表达和系统发育信息相关联，对糖转运蛋白进行去孤儿化或鉴定孤儿糖底物的转运蛋白，可以优化丝状真菌对食品工业副产物和农业废物的再利用，以创造经济价值并减少其对环境的影响。关键点：•粗糙脉孢菌基因组包含 30 个未描述的假定糖转运蛋白基因。•转运蛋白表达和糖摄取谱的相关性可帮助鉴定孤儿糖底物的转运蛋白。•CDT-1、CDT-2 和 NCU00809 是粗糙脉孢菌中乳制副产物乳糖运输的关键因素。
