蓝细菌糖原代谢动态控制策略开发及其生理和代谢影响研究

Cyanobacteria are ideal model organisms for investigating photosynthesis mechanisms and developing photosynthetic cell factories. Glycogen metabolism is an essential natural carbon sink mechanism in cyanobacteria. It is important to understand and regulate cyanobacteria glycogen metabolism for rewiring photosynthesis derived carbon & energy flow and optimizing the robustness and performances of cyanobacteria chassis cells. For more comprehensive understanding of glycogen metabolism and more effective harnessing of carbon & energy flow, we propose to develop a modular dynamic control system of glycogen metabolism in cyanobacteria. The glycogen metabolism would be engineered and regulated in the synthesis and degradation pathways simultaneously, utilizing tools and strategies of synthetic biology and metabolic engineering. With this system, the synthesizing activity of glycogen, degrading activity of glycogen, contents of glycogen, and turnover rates of glycogen in cyanobacteria could be quantitatively regulated and dynamically evaluated. Based on this system, the influences of glycogen metabolism on cellular growth, physiology, and robustness of cyanobacteria would be disclosed with –omics approaches and physiological & biochemical assays. Taking the photosynthetic production of ethanol as a model case, the relationship between glycogen metabolism and artificial carbon-sink pathways would also be disclosed in this project, aiming to explore novel designing principles for developing photosynthesis driven routes of bioproduction.

蓝细菌是研究光合固碳过程、开发光驱固碳细胞工厂的理想模式生物。糖原代谢是蓝细菌重要的天然碳汇机制，理解糖原的生理和代谢功能，调控糖原代谢状态，对优化蓝细菌胞内碳流和能量流分配，开发稳定、高效的光合微生物底盘细胞具有重要意义。针对蓝细菌糖原代谢调控研究的现状，基于申请人团队前期的工作基础和最新认识，本项目希望通过系统应用合成生物学手段和策略，进一步开发蓝细菌糖原代谢机制的模块化动态控制系统，从合成和降解两个途径进行双向-正交式调控，进而实现对工程藻株中糖原合成速率、降解速率、糖原存量以及周转效率的量化调节和适配研究。在此基础上，通过组学分析和生理生化分析，阐明糖原代谢模式对蓝细菌光合生理生长和抗逆能力的影响和作用机制。本项目还将以乙醇光驱固碳合成为模式，解析糖原代谢为代表的天然碳汇模块与人工碳汇途径的适配机制，探索光驱固碳生物合成路线的设计原则。

蓝细菌是研究光合固碳机制、开发光驱固碳细胞工厂的理想模式生物。糖原代谢是蓝细菌重要的天然碳汇机制，理解糖原的生理和代谢功能，调控糖原代谢状态，对优化蓝细菌胞内碳流和能量流分配，开发稳定、高效的光合微生物底盘细胞具有重要意义。本项目开发应用了新型蓝细菌合成生物技术工具与策略，在合成和降解两个环节上实现了对糖原代谢关键基因表达水平以及糖原积累水平的定量调控，解析了糖原代谢对聚球藻细胞生长速度、盐胁迫耐受性、高pH耐受性以及作为光合细胞工厂生产效能的影响；此外，还在全局层面进行拓展，发展了通过ATP合成酶扰动改变细胞能量代谢状态、调节糖原合成水平的策略，应用该策略，成功优化了产蔗糖和海藻糖聚球藻细胞工厂合成能力。在本项目资助下，还针对糖原代谢调节策略以及相关合成生物技术在未来高光效底盘以高效能光合细胞工厂开发方面的应用前景进行了总结与展望，提出了新的认识和观点，在权威生物技术期刊发表多篇高水平综述论文。