本项目以大肠杆菌非特异性跨内膜转运糖分子为目的，研究内容包括：利用栓塞结构域和氨基酸孔环的理性突变，解除SecY蛋白转位通道对水溶性物质的严格密封，削弱细胞内膜对糖分子的屏障作用；结合突变型SecY通道、SARS病毒外壳蛋白SCVE和糖类激酶，构建简单扩散跨膜系统及磷酸化辅助系统；以简单扩散跨膜系统替代木糖、阿拉伯糖、乳糖和纤维二糖转运系统；结合简单扩散跨膜系统和磷酸化辅助系统替代葡萄糖、果糖和甘露糖转运系统；尝试新型糖运输系统在混糖发酵制备木糖醇中的应用。此外，拟探讨简单扩散跨膜系统的设计、构建原理以及简单扩散跨膜系统和磷酸化辅助系统的适配机制，阐明简单扩散跨膜系统克服底物狭窄、“饱和现象”、抑制物敏感和“诱导物排斥”的实现机理和调控策略。本项目有望为大肠杆菌提供新的糖转运策略，研究成果有助于进一步拓展大肠杆菌在代谢工程和合成生物学中的应用前景。

The main purpose of this project is to realize the non-specific transport of sugars across the inner membrane of Escherichia coli. This research includes the following key contents: Release of the SecY protein translocation channel from fully preventing the permeation of the water-soluble substances by rational mutation of its plug and pore ring residues, thus weakening the diffusion barrier of sugars across the inner membrane. Using of the mutant SecY channel, the SARS shell protein SCVE and the sugar kinase to construct a simple-diffusion transmembrane system and a phosphorylation supplementary system. The replacement of the transport system of xylose, arabinose, lactose or cellobiose with the simple-diffusion system will be tried, and the combination of the simple-diffusion system and the phosphorylation supplementary system will be employed to replace the transport system of glucose, fructose or mannose. The recombinant strains with new sugar transport systems will be used to produce xylitol in a mixed-sugar fermentation process. Moreover, the principles for designing, constructing and co-working of the simple-diffusion system and the phosphorylation supplementary system will be intensively studied. The realization mechanism of overcoming the substrate specificity, saturation phenomenon, inhibitor sensitivity, and inducer exclusion by using the simple-diffusion system will also be discussed. This project is expected to provide a new sugar transport strategy for E. coli, and the results will help to further expand the application prospect of E. coli in metabolic engineering and synthetic biology.