Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan.
Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 11529, Taiwan.
New Phytol. 2019 Sep;223(4):1904-1917. doi: 10.1111/nph.15915. Epub 2019 Jul 3.
Choline kinase catalyzes the initial reaction step of choline metabolism that produces phosphocholine, a prerequisite for the biosynthesis of a primary phospholipid phosphatidylcholine. However, the primary choline kinase and its role in plant growth remained elusive in seed plants. Here, we showed that Arabidopsis CHOLINE/ETHANOLAMINE KINASE 1 (CEK1) encodes functional CEK that prefers choline than ethanolamine as a substrate in vitro and affects contents of choline and phosphocholine but not phosphatidylcholine in vivo. CEK1 is localized at endoplasmic reticulum (ER); upon tunicamycin-induced ER stress, a null mutant of CEK1 showed hypersensitive phenotype in seedlings, albeit with no enhanced choline kinase activity. Our results demonstrate that CEK1 is a primary ER-localized choline kinase in vivo that is required for ER stress tolerance possibly through the modulation of choline metabolites.
胆碱激酶催化胆碱代谢的初始反应步骤，产生磷酸胆碱，这是合成主要磷脂磷脂酰胆碱的前提。然而，在种子植物中，主要的胆碱激酶及其在植物生长中的作用仍然难以捉摸。在这里，我们表明拟南芥胆碱/乙醇胺激酶 1（CEK1）编码功能性 CEK，它在体外优先选择胆碱而不是乙醇胺作为底物，并且在体内影响胆碱和磷酸胆碱的含量，但不影响磷脂酰胆碱的含量。CEK1 定位于内质网（ER）；在衣霉素诱导的 ER 应激下，CEK1 的 null 突变体在幼苗中表现出超敏表型，尽管胆碱激酶活性没有增强。我们的结果表明，CEK1 是体内主要的内质网定位的胆碱激酶，它可能通过调节胆碱代谢物来耐受 ER 应激是必需的。
