Ni Yu, Guo Yan-Jun
College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China.
Yi Chuan. 2008 May;30(5):561-7. doi: 10.3724/sp.j.1005.2008.00561.
Very long chain fatty acids (VLCFAs) play a comprehensive role in organisms. They are essential biological components in seed storage triacylglycerols (TAGs), membrane lipids, and sphingolipids. They also serve as precursors of wax layer compounds. The cuticle covers the aerial surface of land plants, which consists of cutin and wax. The wax, including amorphous intracuticular wax embedded in cutin polymer and epicuticular wax crystalloids that cover the outer plant surface, plays crucial roles in plant growth and development, and adaptation to environment. Biosynthesis of VLCFAs is catalyzed by the fatty acyl-CoA elongase, a membrane-bound enzymatic complex containing 3-ketoacyl-CoA synthase (KCS), 3-ketoacyl-CoA reductase (KCR), 3-hydroxacyl-CoA dehydratase (HCD), and trans-2, 3-enoyl-CoA reductase (ECR). Very long chain fatty acid wax precursors flux into cuticular wax biosynthetic pathways through acyl reduction and decarbonylation, and then are converted to all kinds of wax components. This article reviews the functions of VLCFAs and cuticular wax, and the recent progress in cloning and characterization of genes encoding enzymes involved in catalyzing VLCFAs and cuticular wax biosynthesis. The problems existing in researches of wax genes are also discussed.
超长链脂肪酸(VLCFAs)在生物体中发挥着广泛作用。它们是种子储存三酰甘油(TAGs)、膜脂和鞘脂中的重要生物成分。它们还作为蜡层化合物的前体。角质层覆盖陆地植物的地上表面,由角质和蜡质组成。蜡质,包括嵌入角质聚合物中的无定形角质层内蜡质和覆盖植物外表面的角质层外蜡质晶体,在植物生长发育和适应环境方面发挥着关键作用。超长链脂肪酸的生物合成由脂肪酰基辅酶A延长酶催化,该酶是一种膜结合酶复合物,包含3-酮酰基辅酶A合酶(KCS)、3-酮酰基辅酶A还原酶(KCR)、3-羟基酰基辅酶A脱水酶(HCD)和反式-2,3-烯酰基辅酶A还原酶(ECR)。超长链脂肪酸蜡质前体通过酰基还原和脱羰作用进入角质层蜡质生物合成途径,然后转化为各种蜡质成分。本文综述了超长链脂肪酸和角质层蜡质的功能,以及催化超长链脂肪酸和角质层蜡质生物合成的相关酶基因克隆与表征的最新进展。同时也讨论了蜡质基因研究中存在的问题。