谷氨酸棒杆菌中木糖主要通过葡萄糖PTS系统转运，因此，葡萄糖对木糖转运的抑制成为其同步利用葡萄糖和木糖的主要障碍。同时，谷氨酸棒杆菌存在一条尚未解析的木糖转运途径：主要异化子超家族（MFS）蛋白，对其深入研究有望成为解决这一问题的关键所在。本项目首先构建高效代谢木糖的谷氨酸棒杆菌，建立木糖转运定量检测体系。在失活葡萄糖PTS系统的基础上，通过分子遗传学手段解析MFS木糖转运蛋白，从而揭示谷氨酸棒杆菌完整的木糖转运系统。将得到的内源MFS木糖转运蛋白，或者合适的外源转运蛋白，进行分子突变和高通量显色筛选，获得解除葡萄糖抑制的突变。根据蛋白结构模拟研究葡萄糖对MFS蛋白转运木糖的抑制机理。在上述基础上，构建高效同步利用葡萄糖和木糖的谷氨酸棒杆菌。项目研究对于深入理解谷氨酸棒杆菌MFS蛋白木糖转运途径具有重要意义，同时为芳香族氨基酸等发酵过程添加木糖和综合利用木质纤维素资源的生产实践奠定基础。

In Corynebacterium glutamicum, xylose translocates through the membrane mainly via glucose-specific PTS system, thus the inhibition of xylose translocation by glucose is the bottleneck of simultaneous consumption of glucose and xylose. Meanwhile there is another xylose translocation pathway: the major facilitator superfamily protein, which is currently unknown. The detailed study of the MFS xylose transporter would provide a way to solve the problem of simultaneous utilization of glucose and xylose by C. glutamicum. This study will firstly construct an efficient xylose-metabolizing C. glutamicum strain and establish a quantitative determination system of xylose translocation. Based on the deletion of PtsG, the MFS xylose transporter will be revealed through gene overexpression and knockout, and consequently the whole xylose translocation system of C. glutamicum will be elucidated. The exogenous MFS protein will be expressed and verified in C. glutamicum, if the endogenous protein cannot be found. Through molecular mutagenesis and high-throughput screening, the mutants of MFS protein which are released from glucose inhibition will be obtained, and the inhibition mechanism of xylose translocation by glucose will be uncovered via protein structure modelling. This study will be helpful for in-depth understanding of MFS xylose transporters, and lay a solid foundation for industrial practices such as aromatic amino acid fermentation and utilization of lignocellulosic materials.