Specificity of Modular Polyketide Synthases

描述（由申请人提供）：细菌I型模块化聚酮酶（PKS）是合成结构多样且与医学相关的天然产物的复杂多功能酶。考虑到它们的模块化组织，I型PKS的操纵对于产生新的大环内酯类抗生素具有巨大的希望，这些抗生素不容易通过标准化学合成方法获得。然而，为了充分利用这一潜力，需要对各种PKS系统进行全面评估。为此，本提案中描述的实验旨在将化学合成与严格的动力学分析和结构生物学相结合，以增强我们对匹克罗霉素PKS系统特异性和催化作用的理解。除了提供有关单个PKS模块动力学的详细信息外，这项工作还将开始揭示吡克罗霉素和红霉素（DEBS）PKS系统之间的底物特异性差异。此外，将通过X射线共结晶研究详细了解吡克罗霉素硫酯酶结构域的特异性。

DESCRIPTION (provided by applicant): Bacterial type I modular polyketide synthases (PKSs) are complex, multifunctional enzymes that synthesize structurally diverse and medicinally relevant natural products. Given their modular organization, the manipulation of type I PKSs holds tremendous promise for the generation of novel macrolide antibiotics that are not easily accessible by standard chemical synthetic approaches. To fully harness this potential, however, a thorough evaluation of a variety of PKS systems is needed. To this end, the experiments described within this proposal seek to interface chemical synthesis with rigorous kinetic analysis and structural biology in an effort to enhance our understanding of specificity and catalysis of the pikromycin PKS system. In addition to providing detailed information regarding the kinetics of individual PKS modules, this work will also begin to uncover substrate specificity differences between the pikromycin and erythromycin (DEBS) PKS systems. Furthermore, a detailed understanding of the specificity of the pikromycin thioesterase domain will be achieved via x-ray co-crystallization studies.