Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (T.M.H., A.M.F., L.K.);Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom (R.H., F.B., J.A.N.);Université de Bordeaux, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France (D.T., S.P., C.D., F.D., J.J.); andCentre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France (D.T., S.P., C.D., F.D., J.J.).
Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (T.M.H., A.M.F., L.K.);Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom (R.H., F.B., J.A.N.);Université de Bordeaux, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France (D.T., S.P., C.D., F.D., J.J.); andCentre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France (D.T., S.P., C.D., F.D., J.J.)
Plant Physiol. 2015 Mar;167(3):682-92. doi: 10.1104/pp.114.253195. Epub 2015 Jan 16.
The extension of very-long-chain fatty acids (VLCFAs) for the synthesis of specialized apoplastic lipids requires unique biochemical machinery. Condensing enzymes catalyze the first reaction in fatty acid elongation and determine the chain length of fatty acids accepted and produced by the fatty acid elongation complex. Although necessary for the elongation of all VLCFAs, known condensing enzymes cannot efficiently synthesize VLCFAs longer than 28 carbons, despite the prevalence of C28 to C34 acyl lipids in cuticular wax and the pollen coat. The eceriferum2 (cer2) mutant of Arabidopsis (Arabidopsis thaliana) was previously shown to have a specific deficiency in cuticular waxes longer than 28 carbons, and heterologous expression of CER2 in yeast (Saccharomyces cerevisiae) demonstrated that it can modify the acyl chain length produced by a condensing enzyme from 28 to 30 carbon atoms. Here, we report the physiological functions and biochemical specificities of the CER2 homologs CER2-LIKE1 and CER2-LIKE2 by mutant analysis and heterologous expression in yeast. We demonstrate that all three CER2-LIKEs function with the same small subset of condensing enzymes, and that they have different effects on the substrate specificity of the same condensing enzyme. Finally, we show that the changes in acyl chain length caused by each CER2-LIKE protein are of substantial importance for cuticle formation and pollen coat function.
非常长链脂肪酸（VLCFAs）的延伸对于质外体脂质的合成需要独特的生化机制。缩合酶催化脂肪酸延伸的第一个反应，决定了脂肪酸延伸复合物接受和产生的脂肪酸的链长。尽管对于所有 VLCFA 的延伸都是必需的，但已知的缩合酶不能有效地合成长于 28 个碳原子的 VLCFA，尽管在角质层蜡和花粉外壁中存在 C28 到 C34 的酰基脂质。先前已经表明拟南芥（Arabidopsis thaliana）eceriferum2（cer2）突变体在长于 28 个碳原子的角质层蜡中存在特异性缺陷，并且 CER2 在酵母（酿酒酵母）中的异源表达表明它可以修饰由缩合酶产生的酰链长度从 28 到 30 个碳原子。在这里，我们通过突变分析和在酵母中的异源表达报告了 CER2 同源物 CER2-LIKE1 和 CER2-LIKE2 的生理功能和生化特异性。我们证明了所有三种 CER2-LIKE 都与相同的一小部分缩合酶一起起作用，并且它们对同一缩合酶的底物特异性有不同的影响。最后，我们表明每个 CER2-LIKE 蛋白引起的酰链长度变化对角质层形成和花粉外壁功能具有重要意义。
