Hexokinase is necessary for glucose-mediated photosynthesis repression and lipid accumulation in a green alga

First author: Melissa S. Roth; Affiliations: University of California, Berkeley (美国加州大学伯克利分校): CA, USA

Corresponding author: Krishna K. Niyogi 

Global primary production is driven largely by oxygenic photosynthesis, with algae as major contributors. The green alga Chromochloris zofingiensis reversibly switches off photosynthesis in the presence of glucose in the light and augments production of biofuel precursors (triacylglycerols; 三酰甘油) and the high-value antioxidant astaxanthin (虾青素). Here we used forward genetics to reveal that this photosynthetic and metabolic switch is mediated by the glycolytic enzyme hexokinase (CzHXK1). In contrast to wild-type, glucose-treated hxk1 mutants do not shut off photosynthesis or accumulate astaxanthin, triacylglycerols, or cytoplasmic lipid droplets. We show that CzHXK1 is critical for the regulation of genes related to photosynthesis, ketocarotenoid synthesis and fatty acid biosynthesis. Sugars play fundamental regulatory roles in gene expression, physiology, metabolism, and growth in plants and animals, and we introduce a relatively simple, emerging model system to investigate conserved eukaryotic sugar sensing and signaling at the base of the green lineage.

全球生态初级生产力主要由产氧光合作用驱动，而藻类则是主要贡献力量。佐夫色绿藻（Chromochloris zofingiensis）在光下存在葡糖的情况下能够可逆地关闭光合反应，并且提高生物燃料前体三酰甘油和高价值抗氧化剂虾青素的产量。本文中，作者利用正向遗传学的方法揭示了佐夫色绿藻中光合和代谢开关是由糖酵解酶己糖激酶CzHXK1所介导的。相比于野生型，用葡糖处理的hxk1突变体并不会关闭光合反应或是积累虾青素、三酰甘油或细胞质脂滴。作者的研究显示CzHXK1对于光合作用、酮类胡萝卜素合成以及脂肪酸生物合成相关基因的调控至关重要。蔗糖在动植物中的基因表达、生理、代谢以及生长中均具有基础调控作用，作者在本文中引入了一个相对简单、越发成熟的模式系统用于研究真核生物保守的蔗糖感应及信号转导。

通讯：Krishna K. Niyogi (https://plantandmicrobiology.berkeley.edu/profile/niyogi)

个人简介：1986年，翰霍普金斯大学，学士；1993年，麻省理工学院，博士。

研究方向：植物的光合作用。

doi: https://doi.org/10.1038/s42003-019-0577-1

Journal: Communications Biology

Published date: September 19, 2019