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

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。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。所列机构为中心，不一定是研究者所在机构。聚酮化合物是一类结构多样的天然产物，具有抗癌、抗菌、降胆固醇和免疫抑制等重要活性。(20世界上最畅销的药物中有%是聚酮化合物。）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。PKS晶体结构的确定将极大地促进PKS通过蛋白质工程或底物工程的药物利用，以产生下一代“非天然”聚酮抗生素。以前，我们解决了两个硫酯酶从红霉素聚酮合酶（DEBS）和苦霉素聚酮合酶，分别晶体结构，和引发酮合酶（朱H）的晶体结构从R1128聚酮合酶利用在SSRL的束时间。这是一个有希望的开始，最终的目标是阐明一个完整的聚酮合酶的高分辨率结构。在过去的6个月里，我们已经开发了几个重要的酮合酶（KS）和酰基转移酶（AT）结构域从DEBS的结构。最近，我们已经从DEBS的模块3和模块5中结晶了天然的和抑制剂结合的KS-AT双结构域蛋白。初步数据表明，这些晶体的作用范围为3-5。目前，我们正在制备这些双结构域的其他晶体以及其他双结构域蛋白质的晶体。SSRL迫切需要Beamtime来解决这些来自模块化PKS的原型蛋白质的晶体结构，目前还没有已知的结构。

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 have pharmacologically important activities such as anti-cancer, antibiotic, cholesterol lowering and immunosuppressive properties. (20% of the top selling drugs in the world are polyketides.) They are synthesized in nature from a limited repertoire of simple carboxylic acids by multifunctional proteins called polyketide synthases (PKSs). Determination of crystal structures of PKSs will greatly facilitate the pharmaceutical utilization of PKSs by protein engineering or substrate engineering to produce the next generation of "unnatural" polyketide antibiotics. Previously, we solved the crystal structures of two thioesterases from erythromycin polyketide synthase (DEBS) and picromycin polyketide synthase, respectively, and the crystal structure of priming ketosynthase (ZhuH) from R1128 polyketide synthase utilizing the beamtime at SSRL. This represents a promising start toward the eventual goal of elucidating the high-resolution structure of a complete polyketide synthase. Within the past 6 months we have developed several important constructs for ketosynthase (KS) and acyl transferase (AT) domains from DEBS. More recently, we have crystallized both native and inhibitor bound KS-AT didomain proteins from module 3 and module 5 of DEBS. Preliminary data has shown that these crystals diffract in the range of 3-5 ¿¿ Currently we are preparing additional crystals of these didomains as well as crystals of other didomain proteins. Beamtime at SSRL is urgently needed to solve the crystal structures of these prototypical proteins from modular PKSs for which no known structure is currently available.