Engineered Biosynthesis of β-Alkyl Tryptophan Analogues
Engineered Biosynthesis of β-Alkyl Tryptophan Analogues
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DOI：
10.1002/anie.201807998
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发表时间：
2018-11-05
影响因子：
16.6
通讯作者：
Arnold, Frances H.
中科院分区：
文献类型：
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作者：
Boville, Christina E.;Scheele, Remkes A.;Arnold, Frances H.
在α和β位置具有双立体中心的非规范氨基酸（ncAAs）是天然产物和治疗药物的宝贵前体。尽管这种具有生物活性的β支链ncaa具有潜在的应用前景，但由于制备它们的多步骤方法效率低下，它们的可用性受到限制。在此，我们报道了一种立体选择性生物催化合成β支化色氨酸类似物的方法，使用了一种工程变体的荧光焦球菌色氨酸合成酶（PfTrpB）， PfTrpB（7E6）。PfTrpB（7E6）是第一个单步合成大体积β -支化色氨酸类似物的生物催化剂，具有27个ncaa。通过x射线晶体学和UV/Vis光谱研究了PfTrpB（7E6）高效催化和广泛底物耐受性的分子基础，发现活性位点和远程突变的结合增加了关键反应中间体的丰度和持久性。PfTrpB（7E6）为β -支链色氨酸构建块的制备提供了一个操作简单、环境友好的平台。
Noncanonical amino acids (ncAAs) with dual stereocenters at the alpha and beta positions are valuable precursors to natural products and therapeutics. Despite the potential applications of such bioactive beta-branched ncAAs, their availability is limited due to the inefficiency of the multistep methods used to prepare them. Herein we report a stereoselective biocatalytic synthesis of beta-branched tryptophan analogues using an engineered variant of Pyrococcus furiosus tryptophan synthase (PfTrpB), PfTrpB(7E6). PfTrpB(7E6) is the first biocatalyst to synthesize bulky beta-branched tryptophan analogues in a single step, with demonstrated access to 27 ncAAs. The molecular basis for the efficient catalysis and broad substrate tolerance of PfTrpB(7E6) was explored through X-ray crystallography and UV/Vis spectroscopy, which revealed that a combination of active-site and remote mutations increase the abundance and persistence of a key reactive intermediate. PfTrpB(7E6) provides an operationally simple and environmentally benign platform for the preparation of beta-branched tryptophan building blocks.