A mechanism-based fluorescence transfer assay for examining ketosynthase selectivity
作者:Gitanjeli Prasad、Lawrence S. Borketey、Tsung-Yi Lin、Nathan A. Schnarr
DOI:10.1039/c2ob26008e
日期:——
Since their discovery, polyketide synthases have received massive attention from researchers hoping to harness their potential as a platform for generating new and improved therapeutics. Despite significant strides toward this end, inherent specificities within the enzymes responsible for polyketide production have severely limited these efforts. We have developed a mechanism-based, fluorescence transfer assay for a key enzyme component of all polyketide synthases, the ketosynthase domain. As demonstrated, this method can be used with both ketosynthase-containing didomains and full modules. As proof of principle, the ketosynthase domain from module 6 of the 6-deoxyerythronolide synthase is examined for its ability to accept a variety of simple thioester substrates. Consistent with its natural hexaketide substrate, we find that this ketosynthase prefers longer, α-branched thioesters and its ability to distinguish these structural features is quite remarkable. Substrate electronics are also tested via a variety of p-substituted aromatic groups. In all, we expect this technique to find considerable use in the field of polyketide biosynthesis and engineering due to its extraordinary simplicity and very distinct visible readout.
自其发现以来,聚酮合酶一直受到研究人员的极大关注,他们希望利用其潜力作为平台,生成新的和改进的治疗药物。尽管在这方面取得了重大进展,但负责聚酮生产的酶中固有的特定性严重限制了这些努力。我们开发了一种基于机制的、通过荧光传递的测定方法,用于所有聚酮合酶的关键酶组成部分,即酮合酶结构域。如所示,这种方法可以用于含有酮合酶的双结构域和完整模块。作为原理验证,我们检验了来自6-脱氧赤酮酸合酶模块6的酮合酶结构域,以评估其对各种简单硫酯底物的接受能力。与其天然六酮底物一致,我们发现该酮合酶偏好较长的、α-分支的硫酯,并且其区分这些结构特征的能力相当显著。通过各种对位取代的芳香族基团也测试了底物电子性质。总之,我们预计这项技术将在聚酮生物合成和工程领域得到广泛应用,因为它极其简单且具有非常明显的可见输出。