Glucosinolates, synthesized by the glucosinolate biosynthesis pathway, are the secondary metabolites used as a defence mechanism in the Brassicaceae plants, including Arabidopsis thaliana. The first committed step in the pathway, catalysed by methylthioalkylmalate (MAM) synthase (EC: 2.3.3.17), is to produce different variants of glucosinolates. Phylogenetic analyses suggest that possibly MAM synthases have been evolved from isopropylmalate synthase (IPMS) by the substitutions of five amino acid residues (L143I, H167L, S216G, N250G, and P252G) in the active site of IPMS due to point mutations. Considering the importance of MAM synthase in Brassicaceae plants, Petersen et al. (2019) made an effort to characterise the MAM synthase (15 MAM1 variants) in vitro by single substitution or double substitutions. In their study, the authors have expressed the variants in E. coli and analysed the amino acids in the cultures of E. coli in vivo. Since modifying the MAM synthases by transgenic approaches could increase the resistance of Brassicaceae plants for enhancing the defence effect of glucosinolates and their degraded products; hence, MAM synthases should be characterised in detail in vivo in A. thaliana along with the structural analysis of the enzyme for meaningful impact and for its imminent use in vivo.

中文翻译：

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硫代葡萄糖苷生物合成：MAM 合酶的作用及其前景。

通过硫代葡萄糖苷生物合成途径合成的硫代葡萄糖苷是十字花科植物（包括拟南芥）中用作防御机制的次生代谢物。由甲基硫代烷基苹果酸 (MAM) 合酶 (EC: 2.3.3.17) 催化的该途径的第一个重要步骤是生产不同的硫代葡萄糖苷变体。系统发育分析表明，由于点突变，IPMS 活性位点中的五个氨基酸残基（L143I、H167L、S216G、N250G 和 P252G）被取代，可能从异丙基苹果酸合酶 (IPMS) 进化出了 MAM 合酶。考虑到 MAM 合酶在十字花科植物中的重要性，Petersen 等人。(2019) 努力通过单取代或双取代在体外表征 MAM 合酶（15 种 MAM1 变体）。在他们的研究中，作者已经在大肠杆菌中表达了这些变体，并在体内分析了大肠杆菌培养物中的氨基酸。由于通过转基因方法修饰MAM合酶可以增加十字花科植物的抗性，从而增强硫代葡萄糖苷及其降解产物的防御作用；因此，MAM 合酶应在拟南芥体内进行详细表征，同时对该酶的结构分析进行有意义的影响及其即将在体内使用。