Gatekeeping Ketosynthases Dictate Initiation of Assembly Line Biosynthesis of Pyrrolic Polyketides
Gatekeeping Ketosynthases Dictate Initiation of Assembly Line Biosynthesis of Pyrrolic Polyketides
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DOI：
10.1021/jacs.1c02371
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发表时间：
2021-05-14
影响因子：
15
通讯作者：
Agarwal, Vinayak
中科院分区：
文献类型：
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作者：
Yi, Dongqi;Acharya, Atanu;Agarwal, Vinayak
聚酮化合物天然产物的装配线生物合成涉及检查点，其中在允许进行聚酮化合物延伸反应之前验证硫代模板化中间体的身份。确定这些检查点是什么以及它们如何运作对于重新编程聚酮组装线至关重要。在这里，我们证明，酮合酶（KS）域可以执行这个看门的作用。通过比较的聚酮酶，延长吡咯基和卤代吡咯基底物的底物特异性，我们发现，KS域，需要区分这两种底物行使高选择性。我们还发现KS活性位点中的氨基酸残基促进了这种选择性，并且这些残基适合于合理的工程改造。另一方面，KS结构域，不需要作出选择性决定，在其天然的生理环境是基板混杂。我们还提供了证据表明，通过非天然载体蛋白将底物递送至聚酮化合物脱氢酶伴随着生物合成效率降低。
Assembly line biosynthesis of polyketide natural products involves checkpoints where identities of thiotemplated intermediates are verified before polyketide extension reactions are allowed to proceed. Determining what these checkpoints are and how they operate is critical for reprogramming polyketide assembly lines. Here we demonstrate that ketosynthase (KS) domains can perform this gatekeeping role. By comparing the substrate specificities for polyketide synthases that extend pyrrolyl and halogenated pyrrolyl substrates, we find that KS domains that need to differentiate between these two substrates exercise high selectivity. We additionally find that amino acid residues in the KS active site facilitate this selectivity and that these residues are amenable to rational engineering. On the other hand, KS domains that do not need to make selectivity decisions in their native physiological context are substrate-promiscuous. We also provide evidence that delivery of substrates to polyketide synthases by non-native carrier proteins is accompanied by reduced biosynthetic efficiency.