Collaborative Research: S-Methylmethionine: A Central Intermediate in Higher Plant Sulfur and Methyl Group Metabolism

我们对植物硫代谢的了解远远落后于对氮和碳代谢的了解。硫代谢现在可以通过分子遗传学的方法来研究，最近已经显示了植物如何还原硫酸盐和合成必需的氨基酸蛋氨酸(Met)。从蛋氨酸开始，对植物硫代谢的研究进展较少。这一区域是代谢的中心，因为硫途径和一碳途径在蛋氨酸及其代谢物S-腺苷蛋氨酸和S-甲硫氨酸水平上相交。它也是环境生物化学的核心，因为Met和SMM是合成DMSP的起点，DMSP是一种保护植物免受盐胁迫的化合物，对生物地球化学硫循环和全球气候具有重要意义。缺乏从蛋氨酸开始的硫代谢的了解是这个项目的基础，该项目解决了两个相关的问题：SMM的功能和DMSP在开花植物中的生物合成途径。通过阐明SMM的功能，我们将进一步了解植物如何控制其Met的含量，Met是人类和动物营养中的一种必需氨基酸。通过展示一些植物如何进化出一种新的途径将SMM转化为保护性化合物DMSP，我们将进一步了解抗逆性的基本机制和硫循环的生物化学。将培训两名博士后和一名博士后。

Our understanding of sulfur metabolism in plants lags far behind that of nitrogen and carbon metabolism. Sulfur metabolism can now be explored via molecular-genetic approaches, which have recently shown how plants reduce sulfate and synthesize the essential amino acid methionine (Met). There has been less progress in understanding plant sulfur metabolism from Met onwards. This area is a hub of metabolism because sulfur-and one-carbon pathways intersect at the level of Met and its metabolites S-adenosylmethionine and S-methylmethionine (SMM). It is also central to environmental biochemistry because Met and SMM are the starting points for the synthesis of dimethylsulfoniopropionate (DMSP), a compound that protects plants from salt stress and is of major significance to the biogeochemical sulfur cycle and global climate. The lack of understanding of sulfur metabolism from Met onwards is the rationale for this project, which addresses two related problems: the functions of SMM, and the biosynthetic pathway of DMSP in flowering plants. By clarifying the functions of SMM we will advance knowledge of how plants control their contents of Met, an essential amino acid in human and animal nutrition. By show how some plants have evolved a novel pathway to convert SMM into the protective compound DMSP we will advance understanding of basic mechanisms of stress resistance and of the biochemistry of the sulfur cycle. Two postdoctoral students and a Ph.D. student will be trained.