The genus Streptomyces is characterized by the production of a wide variety of secondary metabolites with remarkable biological activities and broad antibiotic capabilities. The presence of an unprecedented number of genes encoding hydrolytic enzymes with industrial appeal such as epoxide hydrolases (EHs) reveals its resourceful microscopic machinery. The whole-genome sequence of Streptomyces sp. CBMAI 2042, an endophytic actinobacterium isolated from Citrus sinensis branches, was explored by genome mining, and a putative α/β-epoxide hydrolase named B1EPH2 and encoded by 344 amino acids was selected for functional and structural studies. The crystal structure of B1EPH2 was obtained at a resolution of 2.2 Å and it was found to have a similar fold to other EHs, despite its hexameric quaternary structure, which contrasts with previously solved dimeric and monomeric EH structures. While B1EPH2 has a high sequence similarity to EHB from Mycobacterium tuberculosis, its cavity is similar to that of human EH. A group of 12 aromatic and aliphatic racemic epoxides were assayed to determine the activity of B1EPH2; remarkably, this enzyme was able to hydrolyse all the epoxides to the respective 1,2-diols, indicating a wide-range substrate scope acceptance. Moreover, the (R)- and (S)-enantiomers of styrene oxide, epichlorohydrin and 1,2-epoxybutane were used to monitor enantiopreference. Taken together, the functional and structural analyses indicate that this enzyme is an attractive biocatalyst for future biotechnological applications.

中文翻译：

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来自内生链霉菌的环氧化物水解酶显示出独特的结构特征和广泛的生物催化活性。

链霉菌属的特点是产生多种具有显着生物活性和广泛抗生素能力的次生代谢产物。编码具有工业吸引力的水解酶（例如环氧化物水解酶（EH））的基因数量空前，揭示了其足智多谋的微观机制。链霉菌属的全基因组序列。CBMAI 2042是一种从柑橘枝条中分离出来的内生放线菌，通过基因组挖掘对其进行了探索，并选择了一个假定的α/β-环氧化物水解酶B1EPH2，由344个氨基酸编码，进行功能和结构研究。B1EPH2 的晶体结构以 2.2 Å 的分辨率获得，尽管其具有六聚四级结构，但它与其他 EH 具有相似的折叠，这与之前解决的二聚和单体 EH 结构形成鲜明对比。虽然 B1EPH2 与结核分枝杆菌的 EHB 具有很高的序列相似性，但其空腔与人类 ​​EH 的空腔相似。对一组 12 种芳香族和脂肪族外消旋环氧化物进行了测定，以确定 B1EPH2 的活性；值得注意的是，该酶能够将所有环氧化物水解为各自的 1,2-二醇，表明底物范围广泛。此外，氧化苯乙烯、环氧氯丙烷和1,2-环氧丁烷的(R)-和(S)-对映体被用来监测对映体优先性。总而言之，功能和结构分析表明，这种酶对于未来的生物技术应用来说是一种有吸引力的生物催化剂。