Broad-Spectrum Antimicrobials Targeting the D-Alanine Pathway

描述(申请人提供)：为了响应NIAID的生物防御研究战略计划，我们启动了一项计划，通过抑制丙氨酸消旋酶来发现和开发针对多种细菌病原体的广谱抗菌剂。丙氨酸消旋酶是D-丙氨酸代谢途径中的一种酶，对细菌细胞壁的合成至关重要。这一途径在细菌中高度保守，在人类中几乎不存在，是环丝氨酸的有效靶点，环丝氨酸是一种商业上可用的抗生素，受到靶外毒性的限制。该项目的长期目标是开发安全有效的小分子疗法，针对各种细菌病原体的丙氨酸消旋酶，包括那些具有生物防御重要性的细菌。利用重组结核分枝杆菌丙氨酸外消旋酶建立了一种专有的高通量筛选试验，以筛选新的酶抑制剂。一项初步筛选确定了对结核分枝杆菌具有抗菌活性的有希望的“Hits”，结核分枝杆菌是导致结核病的细菌。这些HIT中至少有一种抑制了多药耐药(MDRTB)的临床分离株。这个项目将扩大我们的丙氨酸消旋酶抑制剂的数量和用途，作为抗感染药物，有效地对抗多种NIAID细菌优先病原体。从抗MDRTB的HIT化合物开始，迭代药物化学和筛选将被用来扩大这些药物对炭疽芽孢杆菌(炭疽杆菌)和耐甲氧西林金黄色葡萄球菌(MRSA)的活性谱。该项目将由来自学术界和工业界的多学科研究人员团队实施，他们的专业知识涵盖高通量筛选、小分子药物化学和结构生物学等领域，他们分享了一种新的广谱丙氨酸外消旋酶抑制剂作为治疗多种细菌病原体的愿景。该项目将采用高通量筛查和药物化学的方法，结合耐多药结核病、MRSA和炭疽的结构生物学和动物模型，以推动筛查命中治疗线索。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治疗。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，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.