Mechanisms of polyketide, amino acid and Polypeptide biosynthesis

生物有机化学和天然产物化学的主要研究目标包括：a）开发研究次生代谢（特别是聚酮和多肽生物合成）的新方法;和B）研究参与氨基酸和肽代谢的酶的机制和抑制。该计划涉及有机化学（例如合成，光谱分析）和生物化学（例如分子生物学，蛋白质表征，酶抑制，NMR溶液结构以及合作，蛋白质的X射线晶体学）中使用的方法的组合。 该计划的一部分集中在真菌组装聚酮化合物的方式上，聚酮化合物是一类通常由乙酸盐构建的次级代谢产物，通常具有重要的生物活性。特别是，将检查洛伐他汀，降胆固醇剂和药物辛伐他汀（Zocor）的前体的组装的细节。这种分子的构建需要聚酮合酶（PKS）酶LovB和烯酰还原酶LovC，它们在35个高度编程的步骤中一起产生洛伐他汀的大部分骨架。我们将研究这个非凡的分子机器的逐步转变，目的是阐明其机制并产生新的药物类似物。类似的方法将用于研究其他三种生物活性真菌聚酮化合物的生物合成。 该计划的第二部分针对细菌素，细菌素是由食物中天然存在的细菌产生的抗菌肽。它们比传统抗生素的效力高出许多数量级，并且有效对抗对当前疗法具有抗性的病原体。特别是，lantibiotics，一类细菌素，含有单硫化物lanthiocin环的化学合成，将与理解结构-活性关系，使更稳定的衍生物的目标进行研究。目标包括lacticin 3147和gallidermin。另一个方面涉及测定苏云金杆菌素生物合成的细节，苏云金杆菌素对危险病原体艰难梭菌核糖体型027有活性。他们的三维结构也将通过新的方法进行检查

The major objectives of the proposed research in bioorganic chemistry and natural products chemistry include: a) development of new approaches to study secondary metabolism (especially polyketide and polypeptide biosynthesis); and b) study of the mechanism and inhibition of enzymes involved in amino acid and peptide metabolism. The program involves a combination of methods used in organic chemistry (e.g. synthesis, spectroscopic analysis) and biochemistry (e.g. molecular biology, protein characterization, enzyme inhibition, NMR solution structures and, in collaboration, x-ray crystallography of proteins). One part of the program focuses on the way fungi assemble polyketides, a class of secondary metabolites typically built from acetate, that often have important biological activity. In particular, the details of assembly of lovastatin, a cholesterol-lowering agent and precursor to the drug simvastatin (Zocor) will be examined. Construction of this molecule requires the polyketide synthase (PKS) enzyme LovB and the enoyl reductase enzyme LovC, which together produce most of the skeleton of lovastatin in 35 highly programmed steps. We will study the step by step transformations of this remarkable molecular machine with the goal of elucidating its mechanism and generating new analogs of the drug. Similar approaches will be used to study biosynthesis of three other biologically active fungal polyketide compounds. A second part of the program targets bacteriocins, which are antimicrobial peptides produced by bacteria that occur naturally in food. They are many orders of magnitude more potent than conventional antibiotics and are effective against pathogens resistant to current therapy. In particular, chemical synthesis of lantibiotics, a class of bacteriocins that contain monosulfide lanthionine rings, will be investigated with the goal of understanding structure-activity relationships and making more stable derivatives. Targets include lacticin 3147 and gallidermin. Another aspect involves determination of the details of biosynthesis of thuricins, which are active against the dangerous pathogen, Clostridium difficile ribotype 027. Their the 3D structures will also be examined by new approaches