Broad-Spectrum Antimicrobials Targeting the D-Alanine Pathway

描述（由申请人提供）：响应NIAID的生物防御研究战略计划，我们已经启动了一项计划，通过抑制丙氨酸消旋酶（d-丙氨酸代谢途径中的一种酶，对细菌细胞壁合成至关重要）来发现和开发针对多种细菌病原体的广谱抗菌剂。这种途径在细菌中高度保守，在人类中几乎不存在，并且是环丝氨酸的有效靶标，环丝氨酸是一种市售抗生素，受脱靶毒性的限制。该项目的长期目标是开发安全有效的小分子疗法，靶向各种细菌病原体中的丙氨酸消旋酶，包括那些具有生物防御重要性的病原体。利用重组结核分枝杆菌丙氨酸消旋酶开发了一种专有的高通量筛选试验，以筛选新的酶抑制剂。一项试点筛选确定了对结核分枝杆菌（引起结核病的细菌）具有抗菌活性的有希望的“命中”。这些药物中至少有一种能抑制耐多药结核病的临床分离株。该项目将扩大我们的丙氨酸消旋酶抑制剂的数量和效用，作为抗多种NIAID细菌优先病原体的有效抗感染药物。从对耐多药结核病有活性的hit化合物开始，迭代药物化学和筛选将用于扩大这些药物对炭疽杆菌（炭疽的病原体）和耐甲氧西林金黄色葡萄球菌（MRSA）的活性谱，耐甲氧西林金黄色葡萄球菌（MRSA）是危及生命的菌血症的病原体。该项目将由来自学术界和工业界的多学科研究人员组成，他们拥有高通量筛选、小分子药物化学和结构生物学等领域的专业知识，他们共同致力于开发一种新型广谱丙氨酸消旋酶抑制剂，作为治疗多种细菌病原体的药物。该项目将采用高通量筛选和药物化学方法，结合耐多药结核病、MRSA和炭疽热的结构生物学和动物模型，推进筛选命中的治疗线索。相关性（见说明书）：该项目的长期产品目标是治疗具有公共卫生和生物防御重要性的细菌感染的广谱疗法。实现这一目标将加强我们国家对自然、意外和故意接触几种病原体的准备工作，并有助于解决新出现的微生物耐药性问题。

DESCRIPTION (provided by applicant): In response to NIAID's Strategic Plan for Biodefense Research, we have initiated a program to discover and develop broad-spectrum antimicrobials that target multiple bacterial pathogens through inhibition of alanine racemase, an enzyme in the D-alanine metabolic pathway that is essential for bacterial cell wall synthesis. This pathway is highly conserved in bacteria, virtually absent in humans, and is a validated target of cycloserine, a commercially available antibiotic that is limited by off-target toxicity. The long-term goal of this project is to develop safe and effective small molecule therapeutics that target alanine racemase in a variety of bacterial pathogens including those of biodefense importance. A proprietary high-throughput screening assay using recombinant Mycobacterium tuberculosis alanine racemase was developed to screen for novel enzyme inhibitors. A pilot screen identified promising 'hits' with antibacterial activity against M. tuberculosis, the bacterium that causes tuberculosis. At least one of these hits inhibits clinical isolates that are multi-drug resistant (MDRTB). This project will broaden the number and utility of our alanine racemase inhibitors as anti-infectives effective against multiple NIAID bacterial priority pathogens. Starting with hit compounds active against MDRTB, iterative medicinal chemistry and screening will be used to broaden the spectrum of activity of these agents against Bacillus anthracis, the causative agent of anthrax, and methicillin-resistant Staphylococcus aureus (MRSA), the causative agent of life threatening bacteremia. This project will be performed by a multidisciplinary team of investigators from academia and industry with expertise encompassing such areas as high-throughput screening, small molecule medicinal chemistry, and structural biology who share a vision of a novel broad-spectrum alanine racemase inhibitor as a therapeutic against multiple bacterial pathogens. This project will employ methods of high-throughput screening and medicinal chemistry coupled with structural biology and animal models of MDR-TB, MRSA and anthrax to advance screening hits towards therapeutic leads. RELEVANCE (See instructions): The long-term product goal of this project is a broad-spectrum therapeutic to treat bacterial infections of public health and biodefense importance. Accomplishing this goal would enhance our national preparedness for natural, accidental and intentional exposure to several pathogens, and help address emerging microbial drug resistance.