Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
Nat Commun. 2017 Dec 12;8(1):2080. doi: 10.1038/s41467-017-02045-7.
Plants produce hundreds of thousands of structurally diverse specialized metabolites via multistep biosynthetic networks, including compounds of ecological and therapeutic importance. These pathways are restricted to specific plant groups, and are excellent systems for understanding metabolic evolution. Tomato and other plants in the nightshade family synthesize protective acylated sugars in the tip cells of glandular trichomes on stems and leaves. We describe a metabolic innovation in wild tomato species that contributes to acylsucrose structural diversity. A small number of amino acid changes in two acylsucrose acyltransferases alter their acyl acceptor preferences, resulting in reversal of their order of reaction and increased product diversity. This study demonstrates how small numbers of amino acid changes in multiple pathway enzymes can lead to diversification of specialized metabolites in plants. It also highlights the power of a combined genetic, genomic and in vitro biochemical approach to identify the evolutionary mechanisms leading to metabolic novelty.
植物通过多步生物合成网络产生成千上万种结构多样的特殊代谢物，包括具有生态和治疗重要性的化合物。这些途径仅限于特定的植物群，是理解代谢进化的绝佳系统。番茄和茄科的其他植物在茎和叶的腺毛尖端细胞中合成具有保护作用的酰化糖。我们描述了野生番茄物种中的一种代谢创新，它有助于酰基蔗糖结构的多样性。两种酰基蔗糖酰基转移酶中的少数氨基酸变化改变了它们酰基受体的偏好，导致反应顺序的反转和产物多样性的增加。这项研究表明，在多个途径酶中的少数氨基酸变化如何导致植物中特殊代谢物的多样化。它还突出了遗传、基因组和体外生化方法相结合的优势，这种方法可用于识别导致代谢新颖性的进化机制。
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