Therapeutics for Drug-Resistant Bacteria: Myxopyronins

耐药细菌的治疗方法：粘菌素

• 批准号: 8697004
• 负责人: RICHARD H. EBRIGHT
• 金额: $ 121.3万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8697004
• 关键词: Address; Adsorption; Animal Model; Anti-Bacterial Agents; Antibiotics; Antitubercular Agents; Bacterial Infections; Bacterial RNA; Binding; Binding Sites; Biological Assay; Biological Availability; Cells; Clinical; Clostridium difficile; Complex; Cysteine; DNA; DNA-Directed RNA Polymerase; Drug Kinetics; Drug Resistant Tuberculosis; Drug resistance; Drug resistance in tuberculosis; Elements; Enterobacter cloacae; Enterococcus faecalis; Evaluation; Excretory function; Exhibits; Extreme drug resistant tuberculosis; Future; Genetic Transcription; Homology Modeling; In Vitro; Infection; Kilogram; Mammalian Cell; Mediating; Metabolism; Modification; Multi-Drug Resistance; Mycobacterium tuberculosis; Preparation; Procedures; Production; Public Health; Pyrones; RNA Polymerase I; RNA Polymerase II; RNA Polymerase III; Recombinants; Resistance; Rifabutin; Rifampin; Rifamycins; Staphylococcus aureus; Streptococcus pneumoniae; Structure; Technology Transfer; Therapeutic; Toxic effect; Toxicity Tests; Water; Work; analog; base; biodefense; cytotoxicity; design; drug candidate; drug resistant bacteria; efficacy testing; in vivo; inhibitor/antagonist; interfacial; large scale production; methicillin resistant Staphylococcus aureus; mouse model; pathogen; radiochemical; rifapentine; safety testing

DESCRIPTION (provided by applicant): Myxopyronin (Myx) is an ?-pyrone antibiotic that inhibits bacterial RNA polymerase (RNAP) through interactions with the RNAP "switch region," a structural element that mediates conformational changes required for RNAP to bind and retain the DNA template in transcription. Myx does not inhibit eukaryotic RNAP I, RNAP II, or RNAP III. Myx exhibits potent antibacterial activity against Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, Enterobacter cloacae, and Clostridium difficile in culture. Myx exhibits no cross-resistance with the inhibitors of bacterial RNAP in current clinical use in therapy of bacterial infection (the rifamycin antibacterial agents, rifampin, rifapentine, and rifabutin), and exhibits no or minimal cross-resistance with other inhibitors of bacterial RNAP under evaluation for future clinical use in therapy of bacterial infection. In preliminary work, we have shown that Myx functions by inhibiting bacterial RNAP through a binding site and mechanism that are different from those of rifamycin antibacterial agents. We have determined a crystal structure of a bacterial RNAP in complex with Myx, and we have constructed homology models of pathogen RNAP in complex with Myx. The crystal structure and homology models suggest alterations to the structure of Myx that are expected (i) specifically to increase potency against M. tuberculosis RNAP, exploiting a binding-site cysteine residue present in M. tuberculosis RNAP, or (ii) generally to increase potency against a broad spectrum of bacterial RNAP, exploiting a binding-site interfacial water molecule, and other structural features, present in a broad spectrum of bacterial RNAP. In further preliminary work, we have optimized procedures for total synthesis of Myx and Myx analogs, developed procedures for preparation of recombinant pathogen RNAP, and developed procedures for fluorescent and radiochemical assays of pathogen RNAP. We propose to leverage the mechanistic and structural information, synthetic procedures, and assay procedures developed in preliminary work in order to design, synthesize, and evaluate: (i) Myx analogs with increased efficacy against multidrug-resistant and extensively-drug-resistant M. tuberculosis, and (ii) Myx analogs with increased efficacy against a broad spectrum of drug-resistant pathogens. Analogs will be evaluated for inhibition of RNAP in vitro, for antibacterial activity in culture, and for cytotoxicity against mammalian cells in culture. Analogs of high promise will be evaluated for antibacterial activity in small-animal models of infection, and analogs of highest promise will be evaluated for bioavailability, pharmacokinetics, toxicity, and ability to scale synthesis. Primary target pathogens include: M. tuberculosis H37Rv and MDR/XDR, Staphylococcus aureus MSSA and MRSA, Enterococcus faecalis VSE and VRE, Streptococcus pneumoniae, Enterobacter cloacae, and Clostridium difficile. Drug-resistant bacterial infections are a major and growing threat. The proposed work is expected to provide two classes of new drug candidates: (1) antibacterial agents effective against multi-drug-resistant and extensively-drug-resistant tuberculosis, and (2) antibacterial agents effective against a broad spectrum of drug-resistant bacterial pathogens, including both public-health-relevant bacterial pathogens and biodefense-relevant bacterial pathogens.

描述（由申请人提供）：Myxopyronin (Myx) 是一种 β-吡喃酮抗生素，通过与 RNAP“转换区”相互作用来抑制细菌 RNA 聚合酶 (RNAP)，RNAP“转换区”是介导 RNAP 结合和保留转录中 DNA 模板所需的构象变化的结构元件。 Myx 不抑制真核 RNAP I、RNAP II 或 RNAP III。 Myx 对培养的结核分枝杆菌、金黄色葡萄球菌、肺炎链球菌、粪肠球菌、阴沟肠杆菌和艰难梭菌表现出有效的抗菌活性。 Myx 与目前临床用于治疗细菌感染的细菌 RNAP 抑制剂（利福霉素抗菌剂、利福平、利福喷汀和利福布丁）不表现出交叉耐药性，并且与正在评估未来临床用于治疗细菌感染的其他细菌 RNAP 抑制剂不表现出交叉耐药性或具有极小的交叉耐药性。在初步工作中，我们已经证明 Myx 通过与利福霉素抗菌剂不同的结合位点和机制抑制细菌 RNAP 发挥作用。我们确定了细菌RNAP与Myx复合物的晶体结构，并构建了病原体RNAP与Myx复合物的同源模型。晶体结构和同源性模型表明对 Myx 结构的改变预期（i）利用结核分枝杆菌 RNAP 中存在的结合位点半胱氨酸残基，特异性地增加针对结核分枝杆菌 RNAP 的效力，或（ii）利用广泛存在的结合位点界面水分子和其他结构特征，一般增加针对广谱细菌 RNAP 的效力。 细菌 RNAP 谱。在进一步的前期工作中，我们优化了Myx和Myx类似物的全合成程序，开发了重组病原体RNAP的制备程序，并开发了病原体RNAP的荧光和放射化学测定程序。我们建议利用前期工作中开发的机制和结构信息、合成程序和测定程序来设计、合成和评估：(i) Myx 类似物对多重耐药和广泛耐药结核分枝杆菌具有更高的功效，以及 (ii) Myx 类似物对广谱耐药病原体具有更高的功效。将评估类似物的体外 RNAP 抑制作用、培养物中的抗菌活性以及对培养物中哺乳动物细胞的细胞毒性。将评估高前景类似物在小动物感染模型中的抗菌活性，并评估高前景类似物的生物利用度、药代动力学、毒性和规模合成能力。主要目标病原体包括：结核分枝杆菌 H37Rv 和 MDR/XDR、金黄色葡萄球菌 MSSA 和 MRSA、粪肠球菌 VSE 和 VRE、肺炎链球菌、阴沟肠杆菌和艰难梭菌。耐药细菌感染是一个主要且日益严重的威胁。拟议的工作预计将提供两类新候选药物：（1）有效对抗多重耐药和广泛耐药结核病的抗菌药物，以及（2）有效对抗广谱耐药细菌病原体的抗菌药物，包括公共卫生相关细菌病原体和生物防御相关细菌病原体。