CRYSTAL STRUCTURES OF POLYKETIDE SYNTHASES: STRUCTURE-BASED DRUG DESIGN OF NOVEL

这个子项目是许多利用 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来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 聚酮化合物是一类结构多样的天然产物，其表现出多种多样的生物活性，包括抗癌、抗生素、抗病毒和免疫抑制特性，在2005年占全球药物市场的300亿美元。它们在自然界中由称为聚酮酶（PKS）的多功能蛋白质从有限的简单羧酸库合成。I型PKS，当前研究的目标具有模块化架构。PKS的晶体结构的测定将大大有助于系统地探索体系的结构特征，并产生关键的见解，如域边界和基板的选择性的关键功能。这将反过来允许通过蛋白质工程或底物工程来修饰PKS以产生下一代“非天然”聚酮化合物产物。在最近的过去，我们已经解决了一个194 kDa的同源二聚体片段的6-脱氧腺苷酸B合酶（6-DEBS）的晶体结构，除了晶体结构的两个硫酯酶分别从6-DEBS和苦霉素聚酮合酶和引发酮合酶（朱）的晶体结构，从R1128聚酮合酶较早地解决利用在SSRL的光束时间。 考虑到聚酮化合物在合成有机化学和药物发现中的重要性，解决这些蛋白质的晶体结构仅仅是利用PKS进行基于结构的药物设计的开始，最终目标是获得各种合成类似物，这些类似物将用作大环药物先导物的文库。在继续我们对这些蛋白质结构的研究中，将利用SSRL的束时间来解析酮合酶（KS）-酰基载体蛋白（ACP）蛋白片段的晶体结构，该蛋白片段将通过来自模块3 DEBS的2个单独结构域的不可逆共价交联获得。

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 are a structurally diverse class of natural products that exhibit a diverse range of pharmacologically relevant activities including anti-cancer, antibiotic, anti-virus, and immunosuppressive properties, accounting for $ 30 billion of the worldwide pharmaceutical market in 2005. They are synthesized in nature from a limited repertoire of simple carboxylic acids by multifunctional proteins called polyketide synthases (PKSs). Type I PKSs, the target of the current study have a modular architecture. Determination of crystal structures of PKSs will greatly aid in systematically exploring the architectural features of the system and yield key insights into critical features such as domain boundary and substrate selectivity. This would in turn allow modification of PKSs by protein-engineering or substrate-engineering to produce the next generation of "unnatural" polyketide products. In the recent past we have solved the crystal structure of a 194 kDa homodimeric fragment of the 6-deoxyerythronolide B synthase(6-DEBS), in addition to the crystal structures of two thioesterases from 6-DEBS and picromycin polyketide synthase respectively and the crystal structure of priming ketosynthase (ZhuH) from R1128 polyketide synthase solved earlier utilizing the beamtime at SSRL. Given the importance of the polyketides in synthetic organic chemistry and drug discovery, solving the crystal structures of these proteins is only the beginning of structure-based drug design utilizing PKSs with the ultimate goal of accessing a variety of synthetic analogs which would serve as a library of macrocycle drug leads. In continuation with our studies on the structure of these proteins, beamtime at SSRL will be utilized to solve the crystal structures of a ketosynthase (KS)-acyl carrier protein (ACP) protein fragment which will be obtained via irreversible covalent cross-linking of the 2 individual domains from module 3 DEBS.