Choi Sun Hye, Hong Myoung Ki, Kim Hyeon Joong, Ryoo Nayeon, Rhim Hyewhon, Nah Seung Yeol, Kang Lin Woo
Ginsentology Research Laboratory and Department of Physiology and Bio/Molecular Informatics Center, College of Veterinary Medicine, Konkuk University, Seoul 143-701, Republic of Korea.
Department of Biological Sciences, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Acta Crystallogr D Biol Crystallogr. 2015 May;71(Pt 5):1039-50. doi: 10.1107/S139900471500259X. Epub 2015 Apr 24.
Lysophosphatidic acid (LPA) is a phospholipid growth factor with myriad effects on biological systems. LPA is usually present bound to animal plasma proteins such as albumin or gelsolin. When LPA complexes with plasma proteins, it binds to its cognate receptors with higher affinity than when it is free. Recently, gintonin from ginseng was found to bind to LPA and to activate mammalian LPA receptors. Gintonin contains two components: ginseng major latex-like protein 151 (GLP) and ginseng ribonuclease-like storage protein. Here, the crystal structure of GLP is reported, which belongs to the plant Bet v 1 superfamily, and a model is proposed for how GLP binds LPA. Amino-acid residues of GLP recognizing LPA were identified using site-directed mutagenesis and isothermal titration calorimetry. The resulting GLP mutants were used to study the activation of LPA receptor-dependent signalling pathways. In contrast to wild-type GLP, the H147A mutant did not bind LPA, elicit intracellular Ca(2+) transients in neuronal cells or activate Ca(2+)-dependent Cl(-) channels in Xenopus oocytes. Based on these results, a mechanism by which GLP recognizes LPA and its requirement to activate G protein-coupled LPA receptors to elicit diverse biological responses were proposed.
溶血磷脂酸（LPA）是一种对生物系统有多种作用的磷脂生长因子。LPA通常与动物血浆蛋白如白蛋白或凝溶胶蛋白结合存在。当LPA与血浆蛋白形成复合物时，它与其同源受体的结合亲和力高于其游离状态时。最近，发现人参中的ginsenin可与LPA结合并激活哺乳动物的LPA受体。Ginsenin包含两个成分：人参主要乳胶样蛋白151（GLP）和人参核糖核酸酶样储存蛋白。在此，报道了属于植物Bet v 1超家族的GLP的晶体结构，并提出了GLP如何结合LPA的模型。使用定点诱变和等温滴定量热法鉴定了GLP识别LPA的氨基酸残基。所得的GLP突变体用于研究LPA受体依赖性信号通路的激活。与野生型GLP相比，H147A突变体不结合LPA，不引起神经元细胞内的Ca（2+）瞬变，也不激活非洲爪蟾卵母细胞中的Ca（2+）依赖性Cl（-）通道。基于这些结果，提出了一种GLP识别LPA的机制及其激活G蛋白偶联LPA受体以引发多种生物学反应的要求。
