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首页> 外文期刊>Journal of Molecular Biology >Structural and functional insights into O-methyltransferase from Bacillus cereus.
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Structural and functional insights into O-methyltransferase from Bacillus cereus.

机译：蜡样芽孢杆菌O-甲基转移酶的结构和功能见解。

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The specific substrates, mechanisms, and structures of the bacterial O-methyltransferases (OMTs) are not as well characterized as those of other OMTs. Recent studies have suggested that bacterial OMTs catalyze regiospecific reactions that might be used to produce novel compounds. In this study, we investigated the structural and functional features of an OMT from Bacillus cereus (BcOMT2). This enzyme catalyzes the O-methylation of flavonoids in vitro in an S-adenosylmethionine-dependent and regiospecific manner. We solved the crystal structures of the BcOMT2 apoenzyme and the BcOMT2-S-adenosylhomocysteine (SAH) co-complex at resolutions of 1.8 and 1.2 A, respectively. These structures reveal that the overall structure of dimeric BcOMT2 is similar to that of the canonical OMT but that BcOMT2 also has a unique N-terminal helical region that is responsible for dimerization. The binding of SAH causes both local and remote conformational changes in the dimer interface that stabilize the dimerization of BcOMT2. SAH binding also causes ordering of residues Glu171 to Gly186, which are disordered in the apoenzyme structure and are known determinants of substrate specificity, and thus contributes to formation of the substrate binding pocket. Our structural analysis indicated a resemblance between the active site of BcOMT2 and that of metal-dependent OMTs. Using mutational analysis, we confirmed that BcOMT2 is a Mg(2+)-dependent OMT. These results provide structural and functional insights into the dimerization mechanism and substrate specificity of BcOMT2.
机译：细菌O-甲基转移酶（OMT）的特定底物，机制和结构不如其他OMT表征。最近的研究表明，细菌OMT可以催化可能用于生产新型化合物的区域特异性反应。在这项研究中，我们调查了蜡样芽胞杆菌（BcOMT2）的OMT的结构和功能特征。该酶在体外以S-腺苷甲硫氨酸依赖性和区域特异性方式催化类黄酮的O-甲基化。我们解决了BcOMT2脱辅酶和BcOMT2-S-腺苷同型半胱氨酸（SAH）共络合物的晶体结构，分辨率分别为1.8和1.2A。这些结构表明，二聚体BcOMT2的总体结构与经典OMT相似，但BcOMT2也具有负责二聚化的独特N末端螺旋区。 SAH的结合会导致二聚体界面的局部和远程构象变化，从而稳定BcOMT2的二聚化。 SAH结合还引起残基Glu171至Gly186的排序，其在脱辅酶结构中是无序的，并且是底物特异性的已知决定因素，因此有助于底物结合口袋的形成。我们的结构分析表明，BcOMT2的活性位点与金属依赖性OMT的活性位点相似。使用突变分析，我们确认BcOMT2是Mg（2+）依赖的OMT。这些结果为BcOMT2的二聚化机制和底物特异性提供了结构和功能方面的见解。

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