Xiong Wangdan, Wei Qian, Wu Pingzhi, Zhang Sheng, Li Jun, Chen Yaping, Li Meiru, Jiang Huawu, Wu Guojiang
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China; Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China; Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, PR China.
J Plant Physiol. 2017 Jul;214:152-160. doi: 10.1016/j.jplph.2017.05.003. Epub 2017 May 4.
The β-ketoacyl-acyl carrier protein synthase I (KASI) is involved in de novo fatty acid biosynthesis in many organisms. Two putative KASI genes, JcKASI-1 and JcKASI-2, were isolated from Jatropha curcas. The deduced amino acid sequences of JcKASI-1 and JcKASI-2 exhibit around 83.8% and 72.5% sequence identities with AtKASI, respectively, and both contain conserved Cys-His-Lys-His-Phe catalytic active sites. Phylogenetic analysis indicated that JcKASI-2 belongs to a clade with several KASI proteins from dicotyledonous plants. Both JcKASI genes were expressed in multiple tissues, most strongly in filling stage seeds of J. curcas. Additionally, the JcKASI-1 and JcKASI-2 proteins were both localized to the plastids. Expressing JcKASI-1 in the Arabidopsis kasI mutant rescued the mutant's phenotype and restored the fatty acid composition and oil content in seeds to wild-type, but expressing JcKASI-2 in the Arabidopsis kasI mutant resulted in only partial rescue. This implies that JcKASI-1 and JcKASI-2 exhibit partial functional redundancy and KASI genes play a universal role in regulating fatty acid biosynthesis, growth, and development in plants.
β-酮脂酰-酰基载体蛋白合酶I（KASI）参与许多生物体的从头脂肪酸生物合成。从麻疯树中分离出两个假定的KASI基因，JcKASI-1和JcKASI-2。JcKASI-1和JcKASI-2推导的氨基酸序列与AtKASI的序列同一性分别约为83.8%和72.5%，并且两者都含有保守的半胱氨酸-组氨酸-赖氨酸-组氨酸-苯丙氨酸催化活性位点。系统发育分析表明，JcKASI-2属于一个与几种双子叶植物的KASI蛋白的进化枝。两个JcKASI基因在多个组织中表达，在麻疯树灌浆期种子中表达最强。此外，JcKASI-1和JcKASI-2蛋白都定位于质体。在拟南芥kasI突变体中表达JcKASI-1挽救了突变体的表型，并使种子中的脂肪酸组成和油含量恢复到野生型，但在拟南芥kasI突变体中表达JcKASI-2仅导致部分挽救。这意味着JcKASI-1和JcKASI-2表现出部分功能冗余，并且KASI基因在调节植物脂肪酸生物合成、生长和发育中起普遍作用。
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