Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Republic of Korea.
Department of Life Science, Sogang University, Seoul 04107, Republic of Korea.
J Exp Bot. 2022 May 13;73(9):3004-3017. doi: 10.1093/jxb/erab543.
Fatty acid elongase (FAE), which catalyzes the synthesis of very-long-chain fatty acids (VLCFAs), is a multiprotein complex; however, little is known about its quaternary structure. In this study, bimolecular fluorescence complementation and/or yeast two-hybrid assays showed that homo-interactions were observed in β-ketoacyl-CoA synthases (KCS2, KCS9, and KCS6), Eceriferum2-like proteins [CER2 and CER2-Like2 (C2L2)], and FAE complex proteins (KCR1, PAS2, ECR, and PAS1), except for CER2-Like1 (C2L1). Hetero-interactions were observed between KCSs (KCS2, KCS9, and KCS6), between CER2-LIKEs (CER2, C2L2, and C2L1), and between FAE complex proteins (KCR1, PAS2, ECR, and PAS1). PAS1 interacts with FAE complex proteins (KCR1, PAS2, and ECR), but not with KCSs (KCS2, KCS9, and KCS6) and CER2-LIKEs (CER2, C2L2, and C2L1). Asp308 and Arg309-Arg311 of KCS9 were essential for the homo-interactions of KCS9 and hetero-interactions between KCS9 and PAS2 or ECR. Asp339 of KCS9 is involved in its homo- and hetero-interactions with ECR. Complementation analysis of the Arabidopsis kcs9 mutant by the expression of amino acid-substituted KCS9 mutant genes showed that Asp308 and Asp339 of KCS9 are involved in the synthesis of C24 VLCFAs from C22. This study suggests that protein-protein interaction in FAE complexes is important for VLCFA synthesis and provides insight into the quaternary structure of FAE complexes for efficient synthesis of VLCFAs.
脂肪酸延长酶（FAE），催化极长链脂肪酸（VLCFAs）的合成，是一个多蛋白复合物；然而，其四级结构知之甚少。在这项研究中，双分子荧光互补和/或酵母双杂交试验表明，β-酮酰基辅酶 A 合酶（KCS2、KCS9 和 KCS6）、类 Eceriferum2 蛋白[CER2 和 CER2-Like2（C2L2）]和 FAE 复合物蛋白（KCR1、PAS2、ECR 和 PAS1）存在同源相互作用，但 CER2-Like1（C2L1）除外。KCSs（KCS2、KCS9 和 KCS6）之间、CER2-LIKEs（CER2、C2L2 和 C2L1）之间以及 FAE 复合物蛋白（KCR1、PAS2、ECR 和 PAS1）之间存在异源相互作用。PAS1 与 FAE 复合物蛋白（KCR1、PAS2 和 ECR）相互作用，但不与 KCSs（KCS2、KCS9 和 KCS6）和 CER2-LIKEs（CER2、C2L2 和 C2L1）相互作用。KCS9 的 Asp308 和 Arg309-Arg311 对于 KCS9 的同源相互作用和 KCS9 与 PAS2 或 ECR 之间的异源相互作用是必需的。KCS9 的 Asp339 参与其与 ECR 的同源和异源相互作用。通过表达氨基酸取代的 KCS9 突变基因对拟南芥 kcs9 突变体的互补分析表明，KCS9 的 Asp308 和 Asp339 参与了从 C22 合成 C24 VLCFAs。本研究表明，FAE 复合物中的蛋白质-蛋白质相互作用对于 VLCFA 的合成很重要，并为 FAE 复合物的四级结构提供了见解，以实现 VLCFA 的有效合成。
