研究人员鉴定出一种纤维素合酶样蛋白，这是一种意外的生物合成成分，它与早期途径中的酶相互作用，使植物能够生成类固醇支架。此外，在黑茄（Solanum nigrum）中敲除该基因后，植物缺乏类固醇生物碱和皂苷。
令人意外的是，这些敲除植物还显示类固醇皂苷可以抵御严重的农业害虫。这一发现不仅提供了工程化生产高价值类固醇分子的缺失环节，还明确了类固醇皂苷的生态作用。
研究人员表示，茄科植物从共同的胆固醇前体中生成两大类重要的类固醇衍生天然产物——类固醇糖苷生物碱和类固醇皂苷。尽管每个生物合成步骤的相关基因已经被鉴定出来，但异源生产这些分子的尝试一直未能成功。
附：英文原文
Title: A scaffold protein manages the biosynthesis of steroidal defense metabolites in plants
Author: Marianna Boccia, Danny Kessler, Wibke Seibt, Veit Grabe, Carlos E. Rodríguez López, Dagny Grzech, Sarah Heinicke, Sarah E. O’Connor, Prashant D. Sonawane
Issue&Volume: 2024-10-17
Abstract: Solanaceae plants produce two major classes of valuable sterol derived natural products—steroidal glycoalkaloids and steroidal saponins—from a common cholesterol precursor. Attempts to heterologously produce these molecules have consistently failed, although the genes responsible for each biosynthetic step have been identified. Here we identify a cellulose synthase like protein, an unexpected biosynthetic component that interacts with the early pathway enzymes, enabling steroidal scaffolds production in plants. Moreover, knockout of this gene in black nightshade, Solanum nigrum resulted in plants lacking both steroidal alkaloids and saponins. Unexpectedly, these knockout plants also revealed that steroidal saponins deter serious agricultural insect pests. This discovery provides the missing link to engineer these high value steroidal molecules, and also pinpoints the ecological role for the steroidal saponins.
DOI: ado3409
Source: https://www.science.org/doi/10.1126/science.ado3409