Hoqani Umaima Al, León Rosa, Purton Saul
Applied Biology Section, Applied Sciences Department, Higher College of Technology, University of Technology and Applied Sciences, Al-Khuwair 133, Oman.
Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom.
J King Saud Univ Sci. 2022 Aug;34(6):None. doi: 10.1016/j.jksus.2022.102141.
Terpenoids are a diverse class of naturally occurring compounds consisting of more than 50,000 structurally different molecules and are found in all living organisms. Many terpenoid compounds, in particular those isolated from plants, have applications in various commercial sectors including medicine, agriculture and cosmetics. However, these high value terpenoids are produced in relatively small quantities in their natural hosts and their chemical synthesis for large scale production is costly and complicated. Therefore, there is much focus on producing these compounds in novel biological hosts using metabolic engineering technologies. As a photosynthetic system, the unicellular green alga is of particular interest as the most well-studied model alga with well-established molecular tools for genetic manipulation. However, the direct manipulation of terpenoid biosynthetic pathways in necessitates a thorough understanding of the basic terpenoid metabolism. To gain a better understanding of the methylerythritol phosphate (MEP) pathway that leads to terpenoid biosynthesis in the chloroplast of , hence this study has investigated the effect of over-expressing 1-deoxy-d-xylulose-5-phosphate synthase (DXS) on plastidic downstream terpenoids. We produced marker-free chloroplast transformants of lines that express an additional cyanobacterial gene for DXS. The analysis of terpenoid content for the transgenic line demonstrates that overexpressing DXS resulted in a two-fold decrease in the chlorophyll levels while carotenoid levels showed variable changes: zeaxanthin and antherxanthin levels increased several-fold, lutein levels dropped to approximately half, but β-carotene and violaxanthin did not show a significant change.
萜类化合物是一类多样的天然存在的化合物，由超过50,000种结构不同的分子组成，存在于所有生物体中。许多萜类化合物，特别是从植物中分离出来的那些，在包括医药、农业和化妆品在内的各种商业领域都有应用。然而，这些高价值的萜类化合物在其天然宿主中的产量相对较低，并且其大规模化学合成成本高昂且复杂。因此，人们非常关注利用代谢工程技术在新型生物宿主中生产这些化合物。作为一种光合系统，单细胞绿藻作为研究最充分的模式藻类，具有成熟的用于基因操作的分子工具，因而特别受关注。然而，直接操纵绿藻中的萜类生物合成途径需要对萜类基本代谢有透彻的了解。为了更好地理解导致绿藻叶绿体中萜类生物合成的甲基赤藓糖醇磷酸（MEP）途径，因此本研究调查了过表达1-脱氧-D-木酮糖-5-磷酸合酶（DXS）对质体下游萜类化合物的影响。我们构建了表达额外的用于DXS的蓝细菌基因的绿藻品系的无标记叶绿体转化体。对转基因品系萜类化合物含量的分析表明，过表达DXS导致叶绿素水平下降了两倍，而类胡萝卜素水平呈现出不同的变化：玉米黄质和花药黄质水平增加了几倍，叶黄素水平降至大约一半，但β-胡萝卜素和紫黄质没有显著变化。
