Many terrestrial plants produce large quantities of alkanes for use in epicuticular wax and the pollen coat. However, their carbon chains must be long to be useful as fuel or as a petrochemical feedstock. Here, we focus on Nymphaea odorata, which produces relatively short alkanes in its anthers. We identified orthologs of the Arabidopsis alkane biosynthesis genes AtCER1 and AtCER3 in N. odorata and designated them NoCER1A, NoCER3A, and NoCER3B. Expression analysis of NoCER1A and NoCER3A/B in Arabidopsis cer mutants revealed that N. odorata enzymes cooperated with Arabidopsis enzymes and that NoCER1A produced shorter alkanes than AtCER1, regardless of which CER3 protein it interacted with. These results indicate that AtCER1 frequently uses a C30 substrate, whereas NoCER1A, NoCER3A/B, and AtCER3 react with a broad range of substrate chain lengths. The incorporation of shorter alkanes disturbed the formation of wax crystals required for water repellent activity in stems, suggesting that chain length specificity is important for surface cleaning. Moreover, cultured tobacco cells expressing NoCER1A and NoCER3A/B effectively produced C19–C23 alkanes, indicating that the introduction of the two enzymes is sufficient to produce alkanes. Taken together, our findings suggest that these N. odorata enzymes may be useful for the biological production of alkanes of specific lengths. Homology modeling revealed that CER1s and CER3s share a similar 3D structure that consists of N- and C-terminal domains, in which their predicted active sites are respectively located. We predicted the complex structure of both enzymes and found a cavity that connects their active sites.

中文翻译：

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睡莲中烷烃形成酶 NoCER1A 和 NoCER3A/B 的宽链长度特异性

许多陆生植物产生大量烷烃，用于表皮蜡和花粉皮。然而，它们的碳链必须很长才能用作燃料或石化原料。在这里，我们重点关注睡莲，它在花药中产生相对较短的烷烃。我们鉴定了拟南芥烷烃生物合成基因 AtCER1 和 AtCER3 的直系同源物，并将它们命名为 NoCER1A、NoCER3A 和 NoCER3B。拟南芥 cer 突变体中 NoCER1A 和 NoCER3A/B 的表达分析表明，N. odorata 酶与拟南芥酶协同作用，并且 NoCER1A 产生的烷烃比 AtCER1 更短，无论它与哪种 CER3 蛋白相互作用。这些结果表明 AtCER1 经常使用 C30 底物，而 NoCER1A、NoCER3A/B 和 AtCER3 与各种底物链长度发生反应。较短烷烃的掺入扰乱了茎中防水活性所需的蜡晶体的形成，这表明链长特异性对于表面清洁很重要。此外，表达NoCER1A和NoCER3A/B的培养烟草细胞有效地产生C19-C23烷烃，表明引入这两种酶足以产生烷烃。综上所述，我们的研究结果表明这些 N. odorata 酶可能可用于特定长度烷烃的生物生产。同源建模显示，CER1 和 CER3 具有相似的 3D 结构，由 N 端和 C 端结构域组成，它们的预测活性位点分别位于其中。我们预测了两种酶的复杂结构，并发现了连接它们活性位点的空腔。