群体质量控制系统调控酪氨酸生物合成的机制研究

Synthetic biology, as a promising biotechnology, provides living organisms new functions, which is important to enhance biosynthesis performance for bioproduction. We have used biosensors to develop a non-natural system, called population quality control system (PopQC), for enhancing biosynthesis performance. The system first discloses cell-to-cell variations of the biosynthesis performance within a syngeneic population. (i.e., there are high-performing and low-performing cells). Due to metabolic burdens, the high-performing cells are always got growth-disadvantage and to be dis-functioned, which is a serious problem for the biosynthesis under normal conditions. In contrast, PopQC provides the high-performing cells growth-advantage and facilitates its enrichment in whole population, resulting in performance enhancement. However, basements and regulatory mechanisms of the cell-to-cell variation are unknown, preventing PopQC’s optimization and application. In this study, we will disclose mechanisms for the variations within a syngeneic population and optimize the PopQC technology for tyrosine (a high-valued amino acid) biosynthesis. Transcriptomics, proteomics, and metabolomics will be carried out to figure out the differences between the high-performing and low-performing cells and further uncover the related regulatory mechanism. Moreover, we will optimize the PopQC system by exploring new genetic parts (including transcription factors, promoter DNA, binding sites, and selected markers). Guided by the disclosed mechanism, the optimized PopQC will be applied for the tyrosine bioproduction.

生物合成是合成生物学的重要研究领域，提高生物合成效率对于生物产业具有十分重要的意义。申请人发明的群体质量控制系统不仅揭示了同一基因型的表型差异（即纯培养中存在高效和低效细胞），并且利用该系统通过基因编码的分子传感器调控细胞代谢，赋予高效细胞生长优势并使其在群体中富集，显著提高了整体的生物合成效率。然而，目前对于细胞表型差异的物质基础和调控机制还缺乏深入的理解，阻碍了这一技术系统的优化和推广。本研究拟以酪氨酸生物合成为目标，利用多重合成生物学元件（如启动子、调控蛋白和筛选标记等）构建和优化相对应的群体质量控制系统。通过转录、蛋白质和代谢组学三个维度系统性分析，揭示表型差异的物质基础和调控机制。在此基础上，进一步优化群体质量控制系统提高酪氨酸的生物合成。预期取得的研究进展，不仅可以为酪氨酸生物合成效率提高的创新技术开发提供理论基础，而且可以更广义地指导微生物细胞工厂生物合成调控。

合成生物学利用可再生底物生物合成各种各样的生物产品，其中提高生物合成效率具有十分重要的意义。本研究利用合成生物学和代谢工程的方法构建了多条新颖的合成代谢新途径，以木质素来源的底物（例如苯酚，愈创木酚，阿魏酸和对香豆酸）生物合成了各种芳烃天然产物，包括酪氨酸，红景天苷，羟基酪醇，4-羟基苯乙酸，邻苯二酚，生物碱和高香草酸等。另外，构建了酪氨酸相关的生物分子传感器和群体质量控制系统。为了探索表型差异（高产和低产），基于工程菌株中相同基因异源表达形成的表型差异，探索了表型差异的物质基础。结果揭示了异源表达影响了宿主的中心代谢，合理的异源表达有利于减轻宿主负担提高生物合成效率。最后通过提高效率，酪氨酸的产量达到了9g/L。红景天苷，生物碱和高香草酸等其他芳烃天然产物的产量超过1g/L。本研究不仅为高效合成酪氨酸及芳烃类似物提供了新的策略，而且为有效利用木质素来源的可再生芳烃资源提供了新的思路。