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首页> 外文期刊>Biochimica et biophysica acta: BBA: International journal of biochemistry, biophysics and molecular biololgy. Proteins and Proteomics >Structural and biochemical characterization of the broad substrate specificity of Bacteroides thetaiotaomicron commensal sialidase
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Structural and biochemical characterization of the broad substrate specificity of Bacteroides thetaiotaomicron commensal sialidase

机译：拟肌瘤宽底物特异性的结构和生化表征ThetaioMicron非唾液酸酶

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摘要

Siahdases release the terminal sialic acid residue from a wide range of siahc acid-containing polysacchandes. Bacteroides thetaiotaomicron, a symbiotic commensal microbe, resides in and dominates the human intestinal tract We characterized the recombinant sialidase from B. thetaiotaomicron (BTSA) and demonstrated that it has broad substrate specificity with a relative activity of 97,100 and 64 for 2,3-, 2,6- and 2,8-linked sialic substrates, respectively. The hydrolysis activity of BTSA was inhibited by a transition state analogue, 2-deoxy-2,3-dehydro-N-acetyl neuraminic acid, by competitive inhibition with a Ki value of 35 uM. The structure of BSTA was determined at a resolution of 23 A. This structure exhibited a unique carbohydrate-binding domain (CBM) at its N-terminus (a.a. 23-190) that is adjacent to the catalytic domain (a.a. 191-535). The catalytic domain has a conserved arginine triad with a wide-open entrance for the substrate that exposes the catalytic residue to the surface. Unlike other pathogenic sialidases, the polysaccharide-binding site in the CBM is near the active site and possibly holds and positions the polysaccharide substrate directly at the active site. The structural feature of a wide substrate-binding groove and closer proximity of the polysaccharide-binding site to the active site could be a unique signature of the commensal sialidase BTSA and provide a molecular basis for its pharmaceutical application.
机译：Siahdases从含含SiAHC的含SiAHC的多硅烷烷中释放末端唾液酸残余物。菌株ThetaiOtaomicron，一种共生的共生微生物，占据了人肠道的统治者，我们以来自B. ThetaioTaomicron（BTSA）的重组唾液酸酶，并证明它具有宽的底物特异性，具有97,100和64的相对活性为2,3-，分别为2,6-和2,8-连接的唾液基材。通过竞争性抑制，通过竞争性抑制，BTSA抑制BTSA的水解活性，通过竞争力抑制35μm。 BSTA的结构以分辨率为23 A测定。该结构在其与催化结构域（A.A.191-535）相邻的N-末端（A.A.23-190）的独特碳水化合物结合结构域（CBM）。催化结构域具有保守的精氨酸三合会，具有宽开口入口，用于将催化残余物暴露于表面。与其他致病酶酶不同，CBM中的多糖结合位点在活性位点附近，并且可能将多糖基质直接保持并定位在活性位点。宽衬底结合槽的结构特征和更靠近活性位点的多糖结合位点的接近可能是共生唾液酸酶BTSA的独特签名，并为其制药应用提供分子基础。

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