Whole genome sequencing of Chromochloris zofingiensis UV-mutants to identify glucose-linked phenotype

In this study, we investigated the regulation of photosynthesis and metabolism in C. zofingiensis in response to exogenous glucose. Through a forward genetics screen coupled to whole genome sequencing, we uncovered hexokinase1 (CzHXK1) as a master regulator of photosynthesis, carbon metabolism, and ketocarotenoid (astaxanthin) biosynthesis in C. zofingiensis. The hxk1 mutants are deficient in turning off photosynthesis and accumulating astaxanthin and lipids in the presence of glucose. HXK, a key enzyme in carbon metabolism, generates glucose-6-phosphate (G6P) that can be used in a variety of pathways including glycolysis, the oxidative pentose phosphate pathway, and starch and cell wall biosynthesis. HXK is also known to be an evolutionarily conserved eukaryotic glucose sensor in yeast and plants. In contrast to yeast and plants, C. zofingiensis has a single gene encoding hexokinase. Thus, our work establishes C. zofingiensis as a relatively simple system in which to investigate conserved mechanisms of sugar sensing and signaling in the green lineage.

在本项研究中，我们探讨了光合作用与代谢在C. zofingiensis对外源葡萄糖反应中的调控机制。通过结合全基因组测序的前向遗传筛选，我们揭示了己糖激酶1（CzHXK1）作为C. zofingiensis光合作用、碳代谢以及酮类胡萝卜素（虾青素）生物合成的总调控因子。hxk1突变体在葡萄糖存在的情况下，无法关闭光合作用并积累虾青素和脂质。HXK，碳代谢中的关键酶，生成葡萄糖-6-磷酸（G6P），该物质可用于多种途径，包括糖酵解、氧化型戊糖磷酸途径以及淀粉和细胞壁的生物合成。HXK还被认为是酵母和植物中进化上保守的真核葡萄糖传感器。与酵母和植物不同，C. zofingiensis仅有一个基因编码己糖激酶。因此，我们的研究将C. zofingiensis确立为一个相对简单的系统，用以研究绿色谱系中糖感知与信号传导的保守机制。