CRYSTAL STRUCTURES OF POLYKETIDE MEGA-SYNTHASE

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 聚酮化合物包括许多具有降低胆固醇（如洛伐他汀）、抗癌（如阿霉素和博莱霉素）和抗生素活性（如四环素和红霉素）的重要药物，具有潜在的艾滋病毒应用。聚酮合酶 (PKS) 是一种多结构域酶复合物，可通过结构单元和修饰反应（包括链还原和环化）的受控变化产生多种聚酮化合物。 PKS 活性的结构和分子基础存在关键差距。为了解决 PKS 配合物的结构，我们结晶了几种衍射系数为 1.7 ? 的 PKS 配合物。 2.8 ¿由于这些复合物的大小，我们无法通过使用单域结构的分子替换来解决它们。我们已经将 PKS 配合物结晶为 Se、Au 和 Pt 衍生物，其内部衍射值达到 2.2 ? 4.0 ¿因此，SSRL 的 Beamtime 将产生巨大的影响，帮助我们完成这个激动人心的项目。作为拟议研究的结果，我们期望确定所有三种多结构域复杂结构，并确定蛋白质-蛋白质相互作用对聚酮化合物环化/终止特异性的重要性。聚酮化合物环对于聚酮化合物的抗生素和抗癌特性至关重要。该申请中提出的研究意义重大，因为其结果使我们能够阐明聚酮化合物如何在分子水平上特异性环化和终止，这是以前从未见过的。从长远来看，该提案的结果将通过 PKS 的结构定向突变体提供医学上有用的化学物质，对公众健康产生重大的积极影响。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Polyketides include many important drugs with cholesterol-lowering (such as lovastatin), anticancer (such as doxorubicin and bleomysin) and antibiotic activities (such as tetracycline and erythromycin) with potential HIV applications. Polyketide synthase (PKS) is a multi-domain enzyme complex that produces a huge variety of polyketides via a controlled variation of building blocks and modification reactions, including chain reduction and cyclization. There is a critical gap in the structure and molecular basis of PKS activity. To solve the PKS complex structures, we have crystallized several PKS complexes that diffract to 1.7 ? 2.8 ¿. Because of the size of these complexes, we could not solve them by molecular replacement using single-domain structures. We have already crystallized the PKS complexes as Se, Au and Pt derivatives that diffract in-house to 2.2 ? 4.0 ¿. Therefore, beamtime at SSRL will have a great impact by helping us bring this exciting project to the finish line. As an outcome of the proposed investigations, we expect to determine all three multi-domain complex structures and determine the importance of protein-protein interaction on the polyketide cyclization/termination specificity. The polyketide ring is vital for the antibiotic and anticancer properties of polyketides. The research proposed in this application is significant, because its outcome allows us to elucidate how polyketides are specifically cyclized and terminated at a molecular level that has not been visualized before. In the long run, the result from this proposal will have a significant positive impact on the public health by providing medically useful chemicals via structure-directed mutants of PKS.