Overproduction of polyketide antimicrobials

描述（由申请人提供）：聚酮类化合物是一类具有临床应用历史的天然产物（如红霉素、FK506、碘伐他汀）。传统的菌株改良工艺是必要的，以使治疗重要的聚酮具有商业吸引力，但耗时和繁琐。这项工作的长期目标是开发聚酮生产过剩的通用方法，然后将这些方法应用于新型聚酮抗菌剂的产生。在本提案中，我们的目标是生产新的红霉素类似物，用于先导生成和酮内酯和莫内酯治疗药物的临床前开发。酮内酯类抗生素是一类对红霉素敏感菌具有活性的新型强效抗生素。Motilides是胃动素受体激动剂，正在开发用于治疗胃轻瘫、胃反流疾病和其他用途。本提案的具体目标是：i.)使用在i期开发的红霉素过量生产系统来表达几个转基因红霉素PKS基因，并产生早期和后期测试所需的完全成熟的红霉素类似物，ii.)调整该系统，使其能够有效地将合成的二酮- snac前体结合到聚酮产物中，并通过前体定向生物合成生产红霉素类似物。作为具体目标iii)，我们计划在广泛使用的放线菌宿主冷色链霉菌（Streptomyces colicolor）中开始开发第二代通用过剩宿主。这些目标将促进处于后期临床前开发阶段的酮内酯和莫内酯化合物的进展，潜在地产生新的开发线索，并扩大通过微生物系统中聚酮合成酶的遗传操作可以实现的结构多样性。此外，建立明确的过剩寄主将有助于分析过剩生产的分子和生理基础。

DESCRIPTION (provided by applicant): Polyketides are a diverse class of natural products with an established history of clinical utility (e.g. erythromycin, FK506, Iovastatin). Conventional strain improvement processes are necessary to make therapeutically important polyketides commercially attractive but are time consuming and tedious. The long term goals of this work are to develop generic approaches to polyketide overproduction and then apply these approaches to the generation of novel polyketide antimicrobials. In this proposal, we are targeting the production of novel erythromycin analogs for lead generation and preclinical development of ketolide and motilide therapeutics. Ketolides are a new class of potent antibiotics with activity against erythromycin sensitive organisms. Motilides are motilin receptor agonists being developed for treatment of gastric pariesis, gastric reflux disease and other uses. The specific aims of this proposal are: i.) to use an erythromycin overproducing system developed in Phase I to express several genetically modified erythromycin PKS genes and produce fully mature erythromycin analogs needed for early and late stage testing, and ii.) to adapt the system to one that will efficiently incorporate synthetic diketide-SNAC precursors into the polyketide product and produce erythromycin analogs by precursor-directed biosynthesis. As specific aim iii), we plan to initiate development of a second generation generic overproduction host in the widely used actinomycete host Streptomyces coelicolor. These aims will facilitate the advancement of ketolide and motilide compounds that are in late stage preclinical development, potentially generate new leads for development, and expand the diversity of structures that can be achieved through the genetic manipulation of polyketide synthases in microbiological systems. Furthermore, the establishment of well-defined overproduction hosts will facilitate analyzing the molecular and physiological basis of overproduction.