Characterization of AmtA, an amidinotransferase involved in the biosynthesis of phaseolotoxins.
Characterization of AmtA, an amidinotransferase involved in the biosynthesis of phaseolotoxins.
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AmtA（一种参与菜豆毒素生物合成的脒基转移酶）的表征
DOI：
10.1002/2211-5463.12071
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发表时间：
2016-06
期刊：
影响因子：
2.6
通讯作者：
Zhao C
中科院分区：
文献类型：
--
作者：
Li M;Chen L;Deng Z;Zhao C
菜豆毒素是由假单胞菌产生的一类氨基磷酸酯类天然产物。两种非蛋白原性氨基酸前体Nδ（N′-磺基-二氨基膦基）-鸟氨酸（PSOrn）和高精氨酸（hArg）参与了PHTs的生物合成。脒基转移酶AmtA以精氨酸和赖氨酸为底物催化hArg的形成。在大肠杆菌系统中过表达并纯化AmtA。体外酶试验表明，它比某些其他脒基转移酶具有更严格的底物特异性。定点诱变实验表明，突变AmtA Met 243 His 244是一种替代，而Met 246是转脒基活性所必需的。
Phaseolotoxins (PHTs), which are produced by Pseudomonas, belong to a family of phosphoramidate natural products. Two nonproteinogenic amino acid precursors, Nδ(N′‐sulfo‐diaminophosphinyl)‐ornithine (PSOrn) and homoarginine (hArg), are involved in biosynthesis of PHTs. Amidinotransferase AmtA catalyses the formation of hArg, with arginine and lysine as substrates. AmtA was overexpressed and purified in an Escherichia coli system. An in vitro enzyme assay showed that it has stricter substrate specificity than certain other amidinotransferases. Site‐directed mutagenesis experiments showed that the mutation AmtA Met243His244 is an alternative while Met246 is essential for the transamidination activity.