Structure, function, and evolution of plant O-methyltransferases
Structure, function, and evolution of plant O-methyltransferases
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DOI：
10.1139/g07-077
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发表时间：
2007-11-01
期刊：
影响因子：
3.1
通讯作者：
Dayanandan, Selvadurai
中科院分区：
文献类型：
--
作者：
Lam, Kevin C.;Ibrahim, Ragai K.;Dayanandan, Selvadurai
植物O-甲基转移酶(OMTs)是一大类酶，可使苯丙类、黄酮类和生物碱等多种次生代谢物的氧原子甲基化。O-甲基化在植物木质素的生物合成、抗逆性和抗病中起着关键作用。为了深入了解植物O-甲基转移酶特殊多样性的进化，并建立一个框架系统发育树，以改进对新发现的OMT类基因序列可能功能的预测，我们对61个具有生化特征的植物OMT蛋白序列进行了比较和系统发育分析。由此产生的系统发育树揭示了两个主要的类群。其中一个基团包括两个姊妹分支，一个包含使羟基肉桂酰辅酶A酯的酚羟基甲基化的咖啡酰辅酶A OMTs(CCoA OMTs)，另一个包含甲基化脂肪族羧基的羧酸OMTs。另一组由剩余的OMT组成，作用于包括羟基肉桂酸、黄酮类和生物碱在内的各种代谢物。这些结果表明，一些OMT可能经历了趋同进化，而另一些则表现出发散进化。CCoA OMT和羧酸OMT中存在大量独特的保守区，这为设计寡核苷酸引物选择性地扩增和鉴定许多植物OMT基因提供了机会。
Plant O-methyltransferases (OMTs) constitute a large family of enzymes that methylate the oxygen atom of a variety of secondary metabolites including phenylpropanoids, flavonoids, and alkaloids. O-Methylation plays a key role in lignin biosynthesis, stress tolerance, and disease resistance in plants. To gain insights into the evolution of the extraordinary diversity of plant O-methyltransferases, and to develop a framework phylogenetic tree for improved prediction of the putative function of newly identified OMT-like gene sequences, we performed a comparative and phylogenetic analysis of 61 biochemically characterized plant OMT protein sequences. The resulting phylogenetic tree revealed two major groups. One of the groups included two sister clades, one comprising the caffeoyl CoA OMTs (CCoA OMTs) that methylate phenolic hydroxyl groups of hydroxycinnamoyl CoA esters, and the other containing the carboxylic acid OMTs that methylate aliphatic carboxyl groups. The other group comprised the remaining OMTs, which act on a diverse group of metabolites including hydroxycinnamic acids, flavonoids, and alkaloids. The results suggest that some OMTs may have undergone convergent evolution, while others show divergent evolution. The high number of unique conserved regions within the CCoA OMTs and carboxylic acid OMTs provide an opportunity to design oligonucleotide primers to selectively amplify and characterize similar OMT genes from many plant species.