Engineering Imine Reductase for Efficient Biosynthesis of 1-Aryl-Tetrahydro-β-Carbolines and Their N-Methylation Products
Engineering Imine Reductase for Efficient Biosynthesis of 1-Aryl-Tetrahydro-β-Carbolines and Their N-Methylation Products
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DOI：
10.1021/acscatal.1c06012
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发表时间：
2022-07
期刊：
影响因子：
12.9
通讯作者：
Jinmei Zhu;Lu Yang;Jiequn Wu;Zixin Deng;X. Qu
中科院分区：
文献类型：
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作者：
Jinmei Zhu;Lu Yang;Jiequn Wu;Zixin Deng;X. Qu
手性1-芳基-四氢-β-咔啉（THβC）是天然产物和药物中的重要亚结构。由于亚胺还原酶（IRED）的骨架结构庞大、刚性差，因此将其应用于该类化合物的对映选择性合成具有重要意义。本研究通过对空间位阻耐受的IRED IR 45的计算机模拟和突变分析，确定了1-苯基二氢-β-咔啉（DHβCs）的关键结合模式。通过改造B亚基中L228′、M250′和E251′的关键残基，显著提高了该酶的底物耐受性，使其能够高效、立体选择性地合成一系列四、Meta、帕拉和多取代的（S）-1-苯基-TH βCs。通过将酶促亚胺还原和全细胞N-甲基化一锅法相结合，我们进一步发展了一种从DHβC底物直接合成（S）-N-甲基1-苯基-TH β C的成本有效的策略。我们的研究结果不仅为重要的1-芳基THβC骨架的生物合成提供了一条有效的途径，而且显著扩展了IRED的底物特异性，这将有助于IRED在其他空间位阻胺合成中的广泛应用。
Chiral 1-aryl-tetrahydro-β-carboline (THβC) is an important substructure in natural products and pharmaceuticals. The application of imine reductase (IRED) for their enantioselective synthesis is attractive yet has not been realized, owing to the bulkiness and rigidness of the framework. In this study, throughin silicoand mutational analysis of the steric hindrance-tolerant IRED IR45, we identified a critical binding mode for 1-phenyl dihydro-β-carbolines (DHβCs). Engineering the key residues at L228′, M250′, and E251′ in the subunit B significantly expanded the substrate tolerance of the enzyme, enabling efficient, stereoselective synthesis of a series ofortho-,meta-,para-, and multi-substituted (S)-1-phenyl-THβCs. By combining enzymatic imine reduction and whole-cell N-methylation in one pot, we further developed a cost-effective strategy to directly synthesize (S)-N-methyl 1-phenyl-THβCs from DHβC substrates. Our results not only provide an effective route to the biosynthesis of the important 1-aryl THβC frameworks but also significantly expand the substrate specificity of IRED, which will be useful for the broad application of IREDs in the synthesis of other sterically hindered amines.