院士团队Plant Cell解开香气谜题

　　

生物通报道，来自中央研究院生物化学研究所特聘研究员兼副院长王惠钧院士研究团队，日前成功解析植物薄荷香味的合成酵素结构，找到调控气味分子功能的机制。这是结构生物学应用在植物界的一个重要研究，成果甚受国际重视，成果文章刊登在《The Plant Cell》。

 

植物的气味本身具有多层生理意义，除了产生各种香气以吸引昆虫播粉助其繁演后代，并于二次代谢、防范病原体、植物间彼此沟通等层面扮演举足轻重的角色。长久以来科学家们试图深入探讨不同气味背后隐藏的自然奥秘，却未曾彻底揭开调控气味分子的生成机制。

 

由王惠钧副院长所带领的院生化所以及国立台湾大学生化科学研究所团队，成功应用X-光衍射学，生物化学及遗传学等研究方法，首次解析发现产生薄荷香味之关键酵素是由两种不同的蛋白质─催化蛋白质及调控蛋白质─所组成。研究指出，借由此两种蛋白质的交互作用，植物中的酵素能有效重新塑造其活性区域，产生适当产物，以利其后续生合成进而衍生出薄荷气味的分子。

 

研究团队指出，不同于现存已知植物酵素结构是由单一蛋白质所组成，薄荷气味合成酵素係两种不同蛋白质所构成。目前学界对其中具备催化功能的蛋白质，无论在结构或功能上已有相当程度的认识，但对于另一种较小型的蛋白质则陌生得多。

 

研究团队经结构生物学研究途径，首次发现这种小型蛋白质对此具催化功能的蛋白质扮演极重要的调控角色。透过本项发现，研究团队也提出此类酵素可能的演化机制。此研究成果，可以延伸应用于香水的开发和芳香疗法的发展，以及新式天然清洁剂和天然驱虫剂的研发。

（生物通 小茜）

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生物通推荐原文摘要

Structure of a Heterotetrameric Geranyl Pyrophosphate Synthase from Mint (Mentha piperita) Reveals Intersubunit Regulation

Tao-Hsin Chang 1, Fu-Lien Hsieh 1, Tzu-Ping Ko 2, Kuo-Hsun Teng 1, Po-Huang Liang 1, and Andrew H.-J. Wang 3*

1 Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan

2 Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan

3 Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan; Core Facilities for Protein Production and X-Ray Structural Analysis, Academia Sinica, Taipei 115, Taiwan

* To whom correspondence should be addressed. E-mail: [e-mail].

 

 

Terpenes (isoprenoids), derived from isoprenyl pyrophosphates, are versatile natural compounds that act as metabolism mediators, plant volatiles, and ecological communicators. Divergent evolution of homomeric prenyltransferases (PTSs) has allowed PTSs to optimize their active-site pockets to achieve catalytic fidelity and diversity. Little is known about heteromeric PTSs, particularly the mechanisms regulating formation of specific products. Here, we report the crystal structure of the (LSU·SSU)2-type (LSU/SSU = large/small subunit) heterotetrameric geranyl pyrophosphate synthase (GPPS) from mint (Mentha piperita). The LSU and SSU of mint GPPS are responsible for catalysis and regulation, respectively, and this SSU lacks the essential catalytic amino acid residues found in LSU and other PTSs. Whereas no activity was detected for individually expressed LSU or SSU, the intact (LSU·SSU)2 tetramer produced not only C10-GPP at the beginning of the reaction but also C20-GGPP (geranylgeranyl pyrophosphate) at longer reaction times. The activity for synthesizing C10-GPP and C20-GGPP, but not C15-farnesyl pyrophosphate, reflects a conserved active-site structure of the LSU and the closely related mustard (Sinapis alba) homodimeric GGPPS. Furthermore, using a genetic complementation system, we showed that no C20-GGPP is produced by the mint GPPS in vivo. Presumably through protein–protein interactions, the SSU remodels the active-site cavity of LSU for synthesizing C10-GPP, the precursor of volatile C10-monoterpenes.