粗糙脉孢菌葡萄糖双转运系统分子机理解析

Glucose transportation is a critical basic question of nutrient metabolism in life science.It has been observed at cell biology level in 1970s, the Neurospora crassa can initiate the different affinity of glucose transport system (system I-low affinity and II-high affinity) upon the low and high glucose concentration in the environment. However, up to date, the key components and the molecular basis of this glucose dual-transport system remains to be uncovered, it greatly slowers the functional understanding the glucose transport system and metabolic engineering it at molecular level in filamentous fungi. . In this project, we will address the molecular mechanism of the glucose dual-transport system in model fungus Neurospora crassa. The key components of system I and system II will be identified combining transcriptome analysis of fungus grown on different gradient glucose condition and the dynamics characterization of glucose transportation for candidate transporters. Further, the comprehensive functional analysis of system I and system II will be conducted through a set of genetics and biochemical experiments. What are the roles of the dual system could play in glucose sensing, transport and signaling in carbon catabolite repression (CCR) will be dissected. The present study will make a great progress for understanding the glucose transport system in filamentous fungi, and will become a key to do metabolic engineering for improving the glucose metabolism in industrial fermentation using filamentous fungi as host .

葡萄糖转运是生命科学营养物质代谢领域的重要基础科学问题。 1970年代细胞生物学研究发现, 粗糙脉孢菌等丝状真菌在环境中存在高浓度和低浓度葡萄糖时,分别启动两套对葡萄糖亲和力不同的糖转运系统（系统I和II，又称高低双系统）来应对。但迄今为止，尚未从分子水平解析双转运系统的转运蛋白组成及其分子机理，极大限制了对丝状真菌葡萄糖转运途径的功能理解和代谢工程改造。本课题将以模式丝状真菌粗糙脉孢菌为对象,通过分析不同葡萄糖浓度梯度下的转录组学,筛选可能的高低双系统转运蛋白；利用课题组已经建立的糖转运蛋白功能研究技术,表征葡萄糖双转运系统生化特性；继而通过组合突变高低双系统，进一步分析该双系统在丝状真菌葡萄糖信号传导和碳阻遏效应中的功能。本课题的开展，将显著促进丝状真菌葡萄糖双转运系统的分子机理解析及其在未来代谢工程研究中的潜在应用。

葡萄糖转运是真菌研究中重要基础科学问题。但迄今为止，在粗糙脉孢菌中，尚未从分子水平解析葡萄糖转运系统的转运蛋白组成及其分子机理，极大限制了对丝状真菌葡萄糖转运途径的功能理解和代谢工程改造。本课题通过分析粗糙脉孢菌不同葡萄糖浓度梯度下的转录组学,克隆鉴定了该菌葡萄糖转运系统核心转运蛋白，整个系统核心包含三个转运蛋白：低亲和力葡萄糖转运蛋白（命名为GLT-1）和高亲和力葡萄糖转运蛋白（命名为HGT-1/2）；并研究了它们的转运特征和调控系统特征，GLT-1具有较高的Km 值（18.42 ± 3.38 mM），而HGT-1/2分别具有很低的Km 值（16.13 ± 0.95 µM和98.97 ± 22.02 µM）。双系统的调控主要由一个核心转录因子Col-26负责调控，同时我们的研究表明，丝状真菌糖转运系统调控机制复杂，除了Col-26外，Rco-3和AMPK途径也参与其中。本研究对深入理解丝状真菌葡萄糖转运机理和工业真菌代谢工程改造生产生物基化学品都有重要推动意义。