Chemically diverse antimicrobials from silent biosynthetic pathways

描述（由申请人提供）：医疗保健相关感染（HAIs）对美国人民的个人和经济福祉构成巨大威胁。在过去十年中，由于若干复合因素（例如，微生物耐药水平提高、免疫功能低下患者人数不断增加以及新型抗菌素产量急剧下降），HAIs造成的死亡率激增。因此，迫切需要开发新的抗真菌和抗菌疗法，以阻止HAIs造成的生命损失。不幸的是，许多现代药物筛选项目依赖于化学贫乏的文库，这严重损害了它们各自的先导发现潜力。许多这些化学文库的一个主要缺点是其组成化合物之间的化合物同质性和结构新颖性的缺乏。本应用程序的目的是使用化学-表观遗传学方法来严格检查真菌中由沉默生物合成途径编码的独特次级代谢物，这些代谢物是新型抗菌剂的来源。我们将验证一个中心假设，即真菌中沉默的天然产物基因簇的激活将为获得化学多样性的次级代谢物提供无与伦比的途径，我们将利用这些代谢物获得新的抗菌和抗真菌先导物。研究无声生物合成途径生产抗菌剂的基本原理是，从这一来源产生的次级代谢物预计在结构和功能上是新颖的；因此，这些化合物有望具有重要的药物开发价值。基于我们研究小组强有力的初步数据，我们设计了三个具体目标来检验中心假设：1)研究化学表观遗传修饰后真菌产生的抗菌活性范围；2)使用生物测定引导的微孔板分离与电喷雾电离飞行时间质谱联用来分离和纯化具有生物活性的天然产物，用于针对一组微生物病原体的测试；3)应用生物系统和半合成技术的结合来探测先前在PI实验室发现的两组独特的抗菌引线的结构-活性特征。这项研究意义重大，因为它利用了一种创新的方法，化学表观遗传学，从真菌中获取隐藏的天然产物。这些化合物代表了一种未开发的生物活性有机分子来源，具有突出的治疗应用。预计这些研究将提供一系列化学上前所未有的天然产品，这些产品将具有极好的先导开发潜力，作为未来美国国立卫生研究院赞助研究的一部分。

DESCRIPTION (provided by applicant): Healthcare-associated infections (HAIs) pose a tremendous threat to the personal and financial wellbeing of the American people. Over the last decade, there has been a surge in mortality due to HAIs as a result of several compounding factors (e.g., increased levels of drug resistance among microbes, escalating numbers of immunocompromised patients, and a sharp decline in the production of new antimicrobials). Consequently, there is a critical need for the development of new antifungal and antibacterial therapeutics to stem the loss of human life caused by HAIs. Unfortunately, many modern drug screening programs rely on chemically impoverished libraries that severely compromise their respective lead discovery potentials. A major shortcoming for many of these chemical libraries is the significant degree of compound homogeneity and a lack of structural novelty among their component compounds. The objective of this application is to use a chemical-epigenetics methodology to critically examine the unique secondary metabolites that are encoded by silent biosynthetic pathways in fungi as a source of novel antimicrobials. We will test the central hypothesis that the activation of silent natural-product gene clusters in fungi will provide unparalleled access to chemically diverse secondary metabolites, which we will use for procuring new antibacterial and antifungal leads. The rationale for investigating silent biosynthetic pathways for the production of antimicrobials is that secondary metabolites emerging from this source are expected to be structurally and functionally novel; thus these compounds are anticipated to have significant drug development value. Based on our research group's strong preliminary data, three specific aims have been designed to test the central hypothesis: 1) investigate the range of antimicrobial activities emerging from fungi following chemical-epigenetic modification, 2) use bioassay-guided microplate fractionation in tandem with electrospray-ionization time-of-flight mass spectrometry to dereplicate and purify bioactive natural products for testing against a panel of microbial pathogens, and 3) apply a combination of biosystematic and semisynthetic techniques to probe the structure- activity features of two unique groups of antimicrobial leads previously discovered in the PI's laboratory. This research is significant because it capitalizes on an innovative methodology, chemical epigenetics, to access cryptic natural products from fungi. These compounds represent an untapped source of bioactive organic molecules with outstanding therapeutic applications. It is anticipated that these studies will provide an array of chemically unprecedented natural products that will have superb lead development potential as part of future NIH-sponsored studies.