探討藍綠菌 Chlorogloeopsis fritschii PCC 9212 之光誘導調控系統

Abstract

利用藍綠菌作為平台的合成生物學近年來蓬勃發展。透過於藍綠菌中誘導表現特定基因，可調控生產生技產品的時機和產量。然而，化學誘導成本高且現有的光誘導啟動子僅適用於少數藍綠菌菌株。本研究旨在開發可廣泛應用於藍綠菌的光誘導表達系統。本研究以Chlorogloeopsis fritschii PCC 9212 作為平台，探討兩種光調控啟動子系統。首先，我們針對遠紅光誘導啟動子PchlFJSC1，設計不同長度的截短版本，並以黃色螢光蛋白作為報導基因評估其在遠紅光下的誘導能力。結果顯示完整啟動子表現活性最佳，截短版本雖仍具活性但誘導效果下降，顯示上游序列能增強啟動子活性。其次，我們分析不同色光對C. fritschii PCC 9212光合色素及相關基因表現的影響，藉此尋找可被藍光誘導的基因。結果發現藍光能顯著提升藻膽蛋白含量，並影響藻膽蛋白體及光系統二的相關基因表現。綜上所述，本研究不僅進一步分析了遠紅光誘導的啟動子系統，也為開發藍光誘導的啟動子提供了基礎，有助於未來藍綠菌光誘導表達系統的建立。

Synthetic biology in cyanobacteria has rapidly advanced. By inducing the expression of specific genes, it is possible to regulate the timing and yield of bioproducts. However, chemical inducers are costly and not eco-friendly, and current light-inducible promoters work only in limited strains. This study aims to develop applicable light-inducible gene expression systems in cyanobacteria. Using Chlorogloeopsis fritschii PCC 9212 as a model, we explored types of light-inducible promoter systems. First, the far-red light-inducible promoter PchlFJSC1 was truncated into several versions and evaluated for inducibility under far-red light using a reporter gene. The full-length promoter showed the strongest activity, while truncated versions had reduced induction, indicating that upstream sequences enhance promoter activity. Second, we examined the effect of different light qualities on pigment content and gene expression to identify potential blue light-responsive genes. Blue light increased phycobiliprotein levels and altered the expression of genes related to phycobilisomes and Photosystem II. This study not only provides further insight into far-red light-inducible promoters but also lays the foundation for developing blue light-inducible promoters, supporting the development of light-inducible systems in cyanobacteria.