Biochemical and structural analysis of substrate promiscuity in plant Mg2+-dependent O-methyltransferases
Biochemical and structural analysis of substrate promiscuity in plant Mg2+-dependent O-methyltransferases
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DOI：
10.1016/j.jmb.2008.02.019
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发表时间：
2008-04-18
影响因子：
5.6
通讯作者：
Stubbs, Milton T.
中科院分区：
文献类型：
--
作者：
Kopycki, Jakub G.;Rauh, Daniel;Stubbs, Milton T.
植物S-腺苷-L-甲硫氨酸依赖性I类天然产物O-甲基转移酶（OMT）与动物邻苯二酚OMT相关，依赖于二价阳离子，对芳香邻位二羟基的Meta位具有严格特异性。虽然这些I类酶的主要活性是咖啡酰辅酶A OMT的甲基化，但不同的子集能够甲基化更广泛的底物，其特征在于混杂的苯丙素类和类黄酮OMT。所观察到的广泛的底物特异性存在于两个区域：N-末端和C-末端附近的可变插入环，其显示两个亚家族之间的序列保守性最低。结构和生物化学数据，基于定点诱变和两种酶类型之间的结构域交换，目前的证据表明，只有小的拓扑结构之间的变化，否则高度保守的3-D结构足以区分酶通才和酶专家在植物天然产物甲基化。
Plant S-adenosyl-L-methionine-dependent class I natural product O-methyltransferases (OMTs), related to animal catechol OMTs, are dependent on bivalent cations and strictly specific for the meta position of aromatic vicinal dihydroxy groups. While the primary activity of these class I enzymes is methylation of caffeoyl coenzyme A OMTs, a distinct subset is able to methylate a wider range of substrates, characterized by the promiscuous phenylpropanoid and flavonoid OMT. The observed broad substrate specificity resides in two regions: the N-terminus and a variable insertion loop near the C-terminus, which displays the lowest degree of sequence conservation between the two subfamilies. Structural and biochemical data, based on site-directed mutagenesis and domain exchange between the two enzyme types, present evidence that only small topological changes among otherwise highly conserved 3-D structures are sufficient to differentiate between an enzymatic generalist and an enzymatic specialist in plant natural product methylation.