Biochemical characterization of a cinnamoyl-CoA reductase from wheat
Biochemical characterization of a cinnamoyl-CoA reductase from wheat
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DOI：
10.1515/bc.2005.065
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发表时间：
2005-06-01
影响因子：
3.7
通讯作者：
Tian, B
中科院分区：
文献类型：
--
作者：
Ma, QH;Tian, B
肉桂酰辅酶A还原酶（CCR）负责单甘酯生物合成中辅酶A酯→环的转化，其可将类苯丙酸衍生的代谢物转移到木质素的生物合成中。为了更好地了解小麦（Triticum aestivum L.）木质素的生物合成，分离编码CCR的cDNA并命名为Ta-CCR 2。DNA杂交分析表明，Ta-CCR 2基因在小麦基因组中以三个拷贝存在。RNA印迹杂交结果表明，Ta-CCR 2在木质化过程中的根和茎组织中表达量最高。通过分子模拟分析了Ta-CCR 2的二级和三维结构。从大肠杆菌纯化的重组Ta-CCR 2蛋白以几乎相似的效率转化阿魏酰CoA、5-OH-阿魏酰CoA、芥子酰CoA和咖啡酰CoA，表明其参与G和S木质素合成。Ta-CCR 2对4-香豆酰辅酶A具有非常低的V-max值，这可能是控制体内代谢流至H木质素的机制。此外，Ta-CCR 2的反应机理进行了分析，其可能的三维结构。讨论了Ta-CCR 2与木质素生物合成的关系。
Cinnamoyl-CoA reductase (CCR) is responsible for the CoA ester -> aldehycle conversion in monolignol biosynthesis, which can divert phenylpropanoid-derived metabolites into the biosynthesis of lignin. To gain a better understanding of lignin biosynthesis in wheat (Triticum aestivum L.), a cDNA encoding CCR was isolated and named Ta-CCR2. DNA hybridization analyses demonstrated that the Ta-CCR2 gene exists in three copies in the wheat genome. RNA blot hybridization indicated that Ta-CCR2 was expressed most abundantly in root and stem tissues that were in the process of lignification. The secondary and three-dimensional structures of Ta-CCR2 were analyzed by molecular modeling. Recombinant Ta-CCR2 protein purified from E coli converted feruloyl CoA, 5-OH-feruloyl CoA, sinapoyl CoA and caffeoyl CoA with almost similar efficiency, suggesting that it is involved in both G and S lignin synthesis. Ta-CCR2 had a very low V-max value for 4-coumaroyl CoA, which may serve as a mechanism to control metabolic flux to H lignin in vivo. Furthermore, the reaction mechanism of Ta-CCR2 was analyzed in relation to its possible three-dimensional structure. The activity of Ta-CCR2 in relation to lignin biosynthesis is discussed.