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
由假单胞菌(PSeudomonas)产生的菜豆毒素(PHT)属于
氨基
磷酸酯
天然产物的家族。两个nonproteinogenic的
氨基酸前体,N δ(N'-
硫代diaminophosphinyl)
鸟氨酸(PSOrn)和
高精氨酸(ħ精
氨酸),参与PHTs的
生物合成。
氨基转移酶AmtA以精
氨酸和赖
氨酸为底物催化h Arg的形成。AmtA在大肠杆菌系统中过表达和纯化。一种在体外酶测定法显示,它比某些其他酰胺基转移酶具有更严格的底物特异性。定点诱变实验表明,AmtA Met243His244突变是替代方案,而Met246对转酰胺基化活性至关重要。