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首页> 外文期刊>Journal of Molecular Biology >Crystal structure of tannase from lactobacillus plantarum
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Crystal structure of tannase from lactobacillus plantarum

机译：植物乳杆菌鞣酸酶的晶体结构

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摘要

Tannins are water-soluble polyphenolic compounds in plants. Hydrolyzable tannins are derivatives of gallic acid (3,4,5-trihydroxybenzoic acid) or its meta-depsidic forms that are esterified to polyol, catechin, or triterpenoid units. Tannases are a family of esterases that catalyze the hydrolysis of the galloyl ester bond in hydrolyzable tannins to release gallic acid. The enzymes have found wide applications in food, feed, beverage, pharmaceutical, and chemical industries since their discovery more than a century ago, although little is known about them at the molecular level, including the details of the catalytic and substrate binding sites. Here, we report the first three-dimensional structure of a tannase from Lactobacillus plantarum. The enzyme displays an α/β structure, featured by a large cap domain inserted into the classical serine hydrolase fold. A catalytic triad was identified in the structure, which is composed of Ser163, His451, and Asp419. During the binding of gallic acid, the carboxyl group of the molecule forges hydrogen-bonding interactions with the catalytic triad of the enzyme while the three hydroxyl groups make contacts with Asp421, Lys343, and Glu357 to form another hydrogen-bonding network. Mutagenesis studies demonstrated that these residues are indispensable for the activity of the enzyme. Structural studies of the enzyme in complex with a number of substrates indicated that the interactions at the galloyl binding site are the determinant force for the binding of substrates. The single galloyl binding site is responsible for the esterase and depsidase activities of the enzyme.
机译：单宁是植物中的水溶性多酚化合物。可水解单宁是没食子酸（3,4,5-三羟基苯甲酸）或其间二元形式的衍生物，可被酯化为多元醇，儿茶素或三萜类单元。鞣酸酶是一种酯酶家族，其催化可水解单宁中的没食子酸酯键的水解以释放没食子酸。自一个多世纪以来发现以来，这些酶已在食品，饲料，饮料，制药和化学工业中得到广泛应用，尽管对它们的分子水平知之甚少，包括催化和底物结合位点的细节。在这里，我们报告植物乳杆菌的鞣酸酶的第一个三维结构。该酶显示α/β结构，其特征是插入经典丝氨酸水解酶折叠中的大帽结构域。在结构中鉴定出催化三联体，其由Ser163，His451和Asp419组成。在没食子酸的结合过程中，分子的羧基与酶的催化三联体形成氢键相互作用，而三个羟基与Asp421，Lys343和Glu357接触形成另一个氢键网络。诱变研究表明，这些残基对于酶的活性是必不可少的。与许多底物复合的酶的结构研究表明，在没食子酰基结合位点的相互作用是决定底物结合的决定力。单一的没食子酰基结合位点负责该酶的酯酶和脱胶酶活性。

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