丝状真菌如神经孢子菌能够吸收和代谢存在的重要糖,例如,在农业和人类的食物废物。然而,迄今为止,丝状真菌中所有推定的糖转运蛋白中只有一小部分被表征,对于许多糖底物,相应的运输者未知。在克拉萨,到目前为止,在42个假定的主要促进子超家族(MFS)型糖转运蛋白中只有14个被鉴定。为了揭示生物技术隐藏的潜力,因此,有必要找到新的策略。通过不同诱导条件后感兴趣的糖的摄取谱与编码预测的N.crassa糖转运蛋白的所有44个基因的表达谱的相关性,以及使用表征的真菌糖转运蛋白序列进行详尽的系统发育分析,我们旨在确定测试糖的转运蛋白候选物。按照这种方法,我们发现许多糖的摄取率和表达强度与专用转运蛋白高度相关,像半乳糖醛酸和阿拉伯糖,而由于功能冗余,由几种转运蛋白转运的糖的相关性是松散的。然而,这种组合方法使我们能够阐明二糖乳糖的摄取系统,乳制品行业的副产品,它由两个主要的纤维糊精转运蛋白CDT-1和CDT-2组成,相关转运蛋白NCU00809的贡献较小。此外,还鉴定了参与甘油转运的非MFS转运蛋白。因此,通过吸收动力学与转运蛋白表达和系统发育信息的相关性,糖转运蛋白的去孤化或鉴定孤儿糖底物的转运蛋白可以提供一种方法来优化丝状真菌对食品工业副产品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:•粗糙神经孢菌基因组包含30个未表征的推定糖转运蛋白基因。•转运蛋白表达和糖摄取谱的相关性可以帮助鉴定孤儿糖底物的转运蛋白。•CDT-1、CDT-2和NCU00809是N.crassa中乳制品副产品乳糖运输的关键参与者。
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.