报告人：陈冠群教授
报告时间：5月9日 15:00-16:00
报告地点：永利集团台阶会议室
报告人简介：
陈冠群，加拿大阿尔伯塔大学农业食品与营养系助理教授，博士生导师，加拿大植物油脂生物技术方向讲席教授 (Canada Research Chair in Plant Lipid Biotechnology)。主要从事植物及微生物脂质生物技术及脂质代谢方向的研究。已编写专著1部，发表论文45篇，其中多篇论文发表于Plant Journal, Plant Physiology, Journal of Experimental Botany, Journal of Biological Chemistry等知名期刊。
主要内容：
De novo phosphatidylcholine (PC) biosynthesis via the Kennedy pathway involves highly endergonic biochemical reactions that must be fine-tuned with energy homeostasis. CTP:phosphocholine cytidylyltransferase (CCT) is an important regulatory enzyme in this pathway. In this study, an important mechanism regulating plant CCT1 activity was identified. Comparative analysis showed that Arabidopsis thaliana CCT1 (AtCCT1) exhibits homologous catalytic and membrane-binding domains to rat CCT1. Homology modelling indicated that AtCCT1 has similar Rossmann fold and localization of active site residues as rat CCT1. On the other hand, the C-terminal phosphorylation domain that is important for stringent regulation in rat CCT1 is apparently missing in plant CCT. Instead, AtCCT1 contains a putative consensus site (Ser187) of a sucrose-related non-fermenting kinase (SnRK1), a kinase involved in energy homeostasis. Phos-tag SDS-PAGE coupled with MS analysis showed that SnRK1 phosphorylates AtCCT1 primarily at this site. Phosphorylated AtCCT1 suffered a substantial reduction in enzyme activity. Protein truncation and liposome binding studies indicated that SnRK1 phosphorylation of AtCCT1 directly affects the catalytic domain instead of interfering with the phosphatidate-mediated activation of the enzyme. Overexpression of AtCCT1 catalytic domain in Nicotiana benthamiana leaves resulted in higher PC content, but its co-expression with SnRK1 reduced this effect. Taken together, our results suggest that SnRK1 mediates the phosphorylation and inactivation of AtCCT1, revealing a new mode of regulation for this key enzyme in plant PC biosynthesis.
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永利集团
2019年5月6日
