Mechanisms of Polyketide, Amino Acid and Polypeptide Biosynthesis

化学生物学、多肽合成和天然产物的拟议研究的主要目标涉及有机化学（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、酶抑制和蛋白质结构）中使用的方法的组合。它主要分为两个方面：一。细菌抗菌肽（氨基酸聚合物）的合成、构效关系及作用机理; II.真菌聚酮酶（PKS）是真菌中的一种大蛋白质，它分解乙酸以产生生物活性分子，其中一些是重要的人类药物。 就抗菌肽的背景而言，超过50%的医院获得性感染是耐药性的，并且相应的细菌病原体现在构成严重的健康威胁。幸运的是，某些肽可以非常有效地破坏这些病原体。我们的目标是了解细菌抗菌肽的结构和作用机制。由细菌产生的抗微生物肽通常比常规抗生素强几个数量级，可以杀死耐药病原体，并且经常结合靶细菌膜中的受体分子。它们可以是核糖体产生的（细菌素）或由非核糖体肽降解酶（例如脂肽）产生。一个中心主题是对这些肽进行合成修饰，以制造更简单、更容易获得的类似物，这些类似物可用于人类以摧毁耐药病原体。靶点包括lantibiotics（乳链菌肽）、硫-C连接肽（thuricins）和lasso肽（microcin J25）。一个关键的目标是了解这些肽与脂质和受体的相互作用，以及导致细菌细胞死亡的膜孔结构。靶标包括脂肽（tridecaptin）（200 kDa）酶（蛋白质），称为聚酮酶（PKS），其操作类似于脂肪酸脱氢酶。20多种重要的药物衍生自已知的聚酮化合物。最终，它们的功能是将乙酸酯、丙酸酯或其他小的前体转化为具有特定长度、官能度和立体化学的链。 我们的目标是阐明高度还原真菌PKS酶的机制，这是显着的分子机器。靶点包括组装洛伐他汀（一种降胆固醇药物和辛伐他汀（Zocor）的前体）、木贼素（抑制HIV）、脱氢弯孢菌素（一种免疫调节剂植物毒素）、细胞松弛素E（一种抗血管生成抗癌剂）和hypothemycin（一种激酶抑制剂和抗癌候选物）的酶。

The major objectives of the proposed research in chemical biology, peptide synthesis and natural products involve combination of methods used in organic chemistry (e.g. synthesis, spectroscopic analysis) and biochemistry (e.g. molecular biology, protein characterization, enzyme inhibition and structure of proteins). It is mostly divided into two areas: I. synthesis, structure-activity relationships and mechanism of bacterial antimicrobial peptides (polymers of amino acids) and II. mechanism of fungal polyketide synthases (PKS), large proteins from fungi that polymerize acetic acid to make bioactive molecules, some of which are important human drugs. In terms of background for the antimicrobial peptides, over 50% of hospital-acquired infections are antibiotic-resistant, and the corresponding bacterial pathogens now pose a serious health threat. Fortunately, certain peptides can destroy these pathogens very effectively. Our goals are to understand the structures and mechanisms of action of antimicrobial peptides from bacteria. Antimicrobial peptides produced by bacteria are often orders of magnitude more potent than conventional antibiotics, can kill resistant pathogens, and frequently bind a receptor molecule in the membrane of target bacteria. They can be ribosomally made (bacteriocins) or produced by nonribosomal peptide synthases (e.g. lipopeptides). A central theme is synthetic modification of such peptides to make simpler accessible analogs that can be used in humans to destroy resistant pathogens. The targets include lantibiotics (nisin), sulfur to -C linked peptides (thuricins) and lasso peptides (microcin J25). A key objective is understanding interactions of such peptides with lipids and receptors as well as resulting membrane pore structures that lead to bacterial cell death. Targets include lipopeptides (tridecaptins) 200 kDa) enzymes (proteins) known as polyketide synthases (PKS) whose operation resembles fatty acid synthases. More than 20 important drugs are derived from known polyketides. Ultimately their function is to polymerize acetate, propionate or other small precursors into chains having specific length, functionality & stereochemistry. Our goals are to elucidate the mechanisms of highly reducing fungal PKS enzymes, which are remarkable molecular machines. The targets include enzymes that assemble lovastatin (a cholesterol-lowering drug and precusor to simvastatin (Zocor)), equisetin (inhibits HIV), dehydrocurvularin (an immunomodulator phytotoxin), cytochalasin E (an anti-angiogenesis anticancer agent) and hypothemycin (a kinase inhibitor & anticancer candidate).