Methylerythritol Phosphate Pathway Inhibitors Targeting Gram-Negative Infections

描述（由申请人提供）：该项目的长期目标是确定一类新的抗生素，靶向对所有革兰氏阴性菌的生存能力至关重要的未开发途径，甲基赤藓糖醇磷酸（MEP）途径。革兰氏阴性菌造成了一半以上的医院获得性（院内）感染，每年造成的损失估计为50亿美元，其中60%是由耐药菌引起的。许多抗生素的过度使用导致耐药性同时上升到危险水平。由于细菌将不会受到导致耐药性的选择压力，预计现有抗生素类别的未来几代的效用期将比全新类别的效用期短。类异戊二烯生物合成的MEP途径代表了开发一类抗生素的新靶点，与现有抗生素类别相比，具有更大的潜力增加效用。类异戊二烯生物合成是所有生物的基本过程。类异戊二烯是最多样化的天然产物之一，具有多种结构特征，大小从十碳单萜到分子量高达150万的天然橡胶不等。尽管有这种多样性，所有的类异戊二烯都是由两种五碳前体合成的：二磷酸异戊烯基（IPP）和二磷酸二甲基烯基（DMAPP）。在自然界中发现了IPP和DMAPP的两种不相关的生物发生途径。mevalate （MVA）途径存在于人类、部分革兰氏阳性菌和植物细胞质中，而MEP途径存在于所有革兰氏阴性菌、部分革兰氏阳性菌和植物质体中。这种自然分布和缺乏特异性靶向MEP途径的药物使其成为抗菌药物的理想新靶点。目前只有一种靶向MEP通路的化合物进行了临床评估，因此，任何靶向MEP通路的新化学实体都代表着一类全新的抗生素。Echelon将利用一种新颖的、专有的全细胞筛选平台来识别特异性靶向MEP通路的化学制剂。这将通过：首先，开发生化工具来表征mep特异性抑制剂（例如测定MIC， IC50，酶靶点）。其次，调整一个经过验证的筛选平台，以允许在途径的每个步骤中识别抑制剂。第三，筛选MEP通路抑制剂的化学多样性文库。第四，描述由于撞击而观察到的抑制。第五，在筛选中确定的支架周围合成集中的化合物文库，从而产生具有更高效力的分子。第六，筛选在最初筛选中获得的命中点，以杀死导致医院感染的革兰氏阴性菌的能力。

DESCRIPTION (provided by applicant): The long-term objective of this project is to identify a new class of antibiotics targeting an underexploited pathway essential for the viability of all Gram-negative bacteria, the methylerythritol phosphate (MEP) pathway. Gram-negative bacteria are responsible for more than half of hospital acquired (nosocomial) infections which cost an estimated $5 billion dollars per year with >60% caused by resistant bacteria. The overuse of many antibiotics has resulted in a concurrent rise in resistance to dangerous levels. Future generations of existing antibiotic classes are expected to have shorter periods of utility than an entirely new class as bacteria will not have been subjected to selective pressure leading to resistance. The MEP pathway for isoprenoid biosynthesis represents a novel target for developing a class of antibiotic with greater potential for increased utility over existing antibiotic classes. Isoprenoid biosynthesis is an essential process of all living organisms. Isoprenoids represent one of the most diverse classes of natural products with a multitude of structural features and ranging in size from the ten-carbon monoterpenes to natural rubber with a molecular weight as high as 1.5 million. Despite this diversity, all isoprenoids are synthesized from two five-carbon precursors: isopententyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Two unrelated pathways for the biogenesis of IPP and DMAPP are found in nature. The mevalonate (MVA) pathway is found in humans, some Gram-positive bacteria and the cytosol of plants, while the MEP pathway is utilized by all Gram-negative bacteria, some Gram-positives and plant plastids. This natural distribution and a dearth of agents specifically targeting the MEP pathway make it an ideal new target for antibacterials. Only one compound targeting the MEP pathway has undergone clinical evaluation, therefore, any new chemical entity targeting this pathway represents an entirely new class of antibiotics. Echelon will utilize a novel, proprietary whole-cell screening platform to identify chemical agents that specifically target the MEP pathway. This will be accomplished by: First, developing biochemical tools for characterizing MEP-specific inhibitors (e.g. determination of MIC, IC50, enzyme target). Second, adapting a validated screening platform to allow for the identification of inhibitors against every step in the pathway. Third, screening chemically diverse libraries for MEP pathway inhibitors. Fourth, characterizing the inhibition observed as a result of hits. Fifth, synthesizing focused libraries of compounds around the scaffolds identified in the screen resulting in a molecule(s) with increased potency. Sixth, screening hits obtained in initial screens for the ability to kill Gram-negative bacteria responsible for nosocomial infections. Bacterial resistance to current antibiotics continues to increase in both hospital and community settings. The goal of this project is to identify novel antibiotics targeting a unique, underexploited pathway. Since there has been no selective pressure for bacteria to become resistant to these antibiotics, it is expected that compounds identified in this project will have a longer duration of utility than subsequent generations of the current antibiotics.