1. 首页 > 资源库 > 中文 > 植物所论文库

Identification of key amino acid residues determining product specificity of 2,3‐oxidosqualene cyclase in Oryza species

作　　者：Xue ZY, Tan ZW, Huang AC, Zhou Y, Sun JC, Wang XN, Thimmappa RB, Stephenson MJ, Osbourn A*, Qi XQ*
影响因子：7.33
刊物名称：New Phytologist
出版年份：2018
卷：218  期：3  页码：1076-1088

论文摘要：

  • Triterpene synthases, also known as 2,3‐oxidosqualene cyclases (OSCs), synthesize diverse triterpene skeletons that form the basis of an array of functionally divergent steroids and triterpenoids. Tetracyclic and pentacyclic triterpene skeletons are synthesized via protosteryl and dammarenyl cations, respectively. The mechanism of conversion between two scaffolds is not well understood.
  • Here, we report a promiscuous OSC from rice (Oryza sativa) (OsOS) that synthesizes a novel pentacyclic triterpene orysatinol as its main product. The OsOS gene is widely distributed in indica subspecies of cultivated rice and in wild rice accessions. Previously, we have characterized a different OSC, OsPS, a tetracyclic parkeol synthase found in japonica subspecies.
  • Phylogenetic and protein structural analyses identified three key amino acid residues (#732, #365, #124) amongst 46 polymorphic sites that determine functional conversion between OsPS and OsOS, specifically, the chair–semi(chair)–chair and chair–boat–chair interconversions. The different orientation of a fourth amino acid residue Y257 was shown to be important for functional conversion
  • The discovery of orysatinol unlocks a new path to triterpene diversity in nature. Our findings also reveal mechanistic insights into the cyclization of oxidosqualene into tetra‐ and pentacyclic skeletons, and provide a new strategy to identify key residues determining OSC specificity.
全文链接：https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.15080
版权所有 © 中国科学院植物研究所　备案号：京ICP备16067583号-24　文保网安备案号：1101080078
地址：北京市海淀区香山南辛村20号　邮编：100093
电话：010-62590835