CRYSTAL STRUCTURES OF POLYKETIDE MEGA-SYNTHASE

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH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 中心，不一定是研究者的机构。 聚酮化合物包括许多具有降胆固醇（如洛伐他汀）、抗癌（如多柔比星和博来霉素）和抗生素活性（如四环素和红霉素）的重要药物，具有潜在的HIV应用。聚酮合酶（PKS）是一种多结构域酶复合物，其通过结构单元的受控变化和修饰反应（包括链还原和环化）产生大量种类的聚酮化合物。在PKS活性的结构和分子基础上存在一个临界缺口。为了解决PKS复合物的结构，我们已经结晶了几个PKS复合物，结晶到1.7？2.8是的由于这些复合物的大小，我们不能解决他们的分子置换使用单域结构。我们已经结晶的PKS配合物作为硒，Au和Pt的衍生物，在内部，以2.2？4.0是的因此，SSRL的beamtime将产生巨大的影响，帮助我们将这个令人兴奋的项目带到终点线。作为拟议的调查结果，我们希望确定所有三个多域复合物的结构，并确定蛋白质-蛋白质相互作用的聚酮环化/终止特异性的重要性。聚酮环对于聚酮化合物的抗生素和抗癌性质是至关重要的。在这项申请中提出的研究是重要的，因为它的结果使我们能够阐明聚酮化合物是如何在分子水平上特异性地环化和终止的，这是以前没有看到的。从长远来看，该提案的结果将对公共健康产生重大的积极影响，通过PKS的结构定向突变体提供医学上有用的化学品。

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.