Ma Xueyan, Koepke Juergen, Panjikar Santosh, Fritzsch Günter, Stöckigt Joachim
Department of Pharmaceutical Biology, Institute of Pharmacy, Johannes Gutenberg-University Mainz, Staudinger Weg 5, D-55099 Mainz, Germany.
J Biol Chem. 2005 Apr 8;280(14):13576-83. doi: 10.1074/jbc.M414508200. Epub 2005 Jan 22.
Vinorine synthase is an acetyltransferase that occupies a central role in the biosynthesis of the antiarrhythmic monoterpenoid indole alkaloid ajmaline in the plant Rauvolfia. Vinorine synthase belongs to the benzylalcohol acetyl-, anthocyanin-O-hydroxy-cinnamoyl-, anthranilate-N-hydroxy-cinnamoyl/benzoyl-, deacetylvindoline acetyltransferase (BAHD) enzyme superfamily, members of which are involved in the biosynthesis of several important drugs, such as morphine, Taxol, or vindoline, a precursor of the anti-cancer drugs vincaleucoblastine and vincristine. The x-ray structure of vinorine synthase is described at 2.6-angstrom resolution. Despite low sequence identity, the two-domain structure of vinorine synthase shows surprising similarity with structures of several CoA-dependent acyltransferases such as dihydrolipoyl transacetylase, polyketide-associated protein A5, and carnitine acetyltransferase. All conserved residues typical for the BAHD family are found in domain 1. His160 of the HXXXD motif functions as a general base during catalysis. It is located in the center of the reaction channel at the interface of both domains and is accessible from both sides. The channel runs through the entire molecule, allowing the substrate and co-substrate to bind independently. Asp164 points away from the catalytic site and seems to be of structural rather than catalytic importance. Surprisingly, the DFGWG motif, which is indispensable for the catalyzed reaction and unique to the BAHD family, is located far away from the active site and seems to play only a structural role. Vinorine synthase represents the first solved protein structure of the BAHD superfamily.
长春罗新碱合酶是一种乙酰转移酶，在萝芙木属植物中抗心律失常单萜吲哚生物碱阿吗灵的生物合成中起着核心作用。长春罗新碱合酶属于苄醇乙酰基、花青素-O-羟基肉桂酰基、邻氨基苯甲酸-N-羟基肉桂酰基/苯甲酰基、去乙酰文多灵乙酰转移酶（BAHD）酶超家族，该家族成员参与了几种重要药物的生物合成，如吗啡、紫杉醇或文多灵，后者是抗癌药物长春碱和长春新碱的前体。长春罗新碱合酶的X射线结构在2.6埃分辨率下得到描述。尽管序列同一性较低，但长春罗新碱合酶的双结构域结构与几种依赖辅酶A的酰基转移酶的结构惊人地相似，如二氢硫辛酰转乙酰酶、聚酮相关蛋白A5和肉碱乙酰转移酶。BAHD家族所有典型的保守残基都存在于结构域1中。HXXXD基序中的His160在催化过程中作为通用碱发挥作用。它位于两个结构域界面处反应通道的中心，并且从两侧都可接近。通道贯穿整个分子，允许底物和共底物独立结合。Asp164指向远离催化位点的方向，似乎具有结构而非催化重要性。令人惊讶的是，对于催化反应不可或缺且BAHD家族特有的DFGWG基序位于远离活性位点的位置，似乎仅起结构作用。长春罗新碱合酶代表了BAHD超家族中首个解析出的蛋白质结构。
