CyaA*腺苷环化酶突变解除葡萄糖对木糖转运阻遏的机制

Glucose and xylose co-utilization is the key to resolve rich and cheap lignocellulose biomass resource utilization. The transport and metabolism of xylose were repressed by glucose repressive effect. Our recent studies found that the inhibition of xylose transport by glucose was removed by CyaA* adenosine cyclase mutation in Escherichia coli. Adenosine cyclase is the main enzyme in the synthesis of cAMP, and the global regulatory factor cAMP-CRP was involved in the expression of mutiple genes. In this project, the transcriptome and proteome of strains containing CyaA* mutation will be analyzed to find out the key genes, and new xylose transporters by gene deletion and overexpression. On the other hand, whether CyaA * mutation has inhibitory effect on glucose transport metabolism. With expectation, this project will obtain a new xylose transporter, and reveal the molecular mechanism of releasing the inhibition of xylose transport by glucose repression. It would provide a theoretical foundation for the construction of the chassis bacteria with utilization glucose and xylose simultaneously.

葡萄糖和木糖共利用是实现丰富廉价的木质纤维素生物质资源化的关键。葡萄糖对木糖的转运和代谢存在阻遏效应。申请人前期研究发现，CyaA*腺苷环化酶突变解除了葡萄糖对木糖转运的抑制。腺苷环化酶是合成cAMP的关键酶，形成的全局调控因子cAMP-CRP参与了细胞多个基因的表达调控。本项目拟对含有CyaA*突变的菌株进行转录组和蛋白组分析，找出CyaA*突变调控的关键基因；通过基因敲除和过表达，鉴定出新的木糖转运蛋白，并完成其功能研究。同时，将研究CyaA*突变是否对葡萄糖转运和代谢有抑制效应。通过本项目的研究，预期将获得新的木糖转运蛋白，阐明解除葡萄糖抑制木糖转运的分子机制，为实现葡萄糖和木糖共利用奠定理论基础。

前期的工作中，申请人的研究团队发现CyaA*突变解除了葡萄糖对木糖利用的阻遏，本项目围绕“CyaA*腺苷环化酶突变解除葡萄糖对木糖转运阻遏”这一关键问题进行了深入的研究。腺苷环化酶CyaA受酶IIAglc-P激活，催化ATP形成cAMP，和CRP蛋白结合生成cAMP-CRP复合物，参与400个基因的调控表达。其已知的一个功能是能够正调控木糖代谢途径基因的表达。通过本项目的执行，证实了腺苷环化酶CyaA具有新的功能，它的突变解除了葡萄糖对木糖转运的抑制。.本项目按照研究计划顺利完成了：（1）含有CyaA*突变的菌株的转录组和蛋白组分析，找出了CyaA*突变调控的关键基因；（2）通过对关键基因敲除和过表达，鉴定出新的木糖转运蛋白XylC*和AraE*，并完成其功能研究；（3）阐明了解除葡萄糖抑制木糖转运的分子机制，为实现葡萄糖和木糖共利用奠定理论基础。（4）发表SCI论文3篇，中文核心1篇，授权专利1项。.上述研究成果，为创建葡萄糖和木糖高效共利用底盘菌株奠定了坚实的基础，为实现木质纤维素水解液的物质转化，切实应用到生产大宗化学品奠定了物质基础。