Discovery of a New Class of Antibacterials that Inhibits Penicillin-Binding Proteins

描述(由申请人提供)：耐甲氧西林金黄色葡萄球菌(MRSA)是医院和社区获得性感染的主要原因。疾病控制和预防中心已将MRSA确定为对公共健康的严重威胁。市场上的许多抗生素在治疗耐甲氧西林金黄色葡萄球菌感染方面不再有效，仅在美国每年就导致1.1万人死亡。目前批准用于治疗MRSA感染的抗生素有万古霉素、利奈唑胺、头孢他林和达托霉素，其中只有利奈唑胺可以口服。此外，所有这四种批准的药物都有抗药性的记录。这突显了开发能够有效治疗这些细菌感染的新的口服抗生素的重要性。 我们发现了一类新的抗菌剂，即喹唑烷酮类化合物，它们在MRSA感染的小鼠模型中是有效的，并表征了它们的作用机制。喹唑烷酮铅为水溶性，具有良好的口服生物利用度，清除率低，无毒，但其分布体积适中。喹唑烷酮与参与细胞壁合成的青霉素结合蛋白(PBP)2a的变构部位结合，并触发活性部位的开放。本方案旨在对喹唑烷酮类化合物进行先导优化，研究喹唑烷酮类化合物与其他抗生素的协同作用，并进一步探讨其作用机理。这项建议是一个跨学科的项目，涉及有机合成、生物化学、微生物学、结构生物学、药理学和感染的动物模型。这些研究将扩大我们在设计有效的抗MRSA化合物和理解这类新的抗菌药方面的知识。

DESCRIPTION (provided by applicant): Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital- and community-acquired infections. MRSA has been identified as a serious threat to public health by the Centers for Disease Control and Prevention. Many antibiotics on the market are no longer effective in treating MRSA infections, which results in >11,000 deaths a year in the United States alone. The currently approved antibiotics for treating MRSA infections are vancomycin, linezolid, ceftaroline, and daptomycin, of which only linezolid can be dosed orally. In addition, resistance has been documented for all four of these approved drugs. This underscores the importance to develop new, orally available antibiotics that can effectively treat these bacterial infections. We have discovered a new class of antibacterial agents, the quinazolinones, which are effective in a mouse model of MRSA infection and characterized their mechanism of action. The lead quinazolinone is water soluble, has good oral bioavailability, low clearance, and is not toxic; however it has a modest volume of distribution. The quinazolinone binds to the allosteric site of penicillin-binding protein (PBP) 2a, an enzyme involved in cell-wall synthesis, and triggers opening of the active site. This proposal aims to perform lead optimization of the quinazolinone class, to investigate the synergy between the quinazolinones and other antibiotics, and to further investigate the mechanism of action of the quinazolinones. This proposal is an interdisciplinary project that involves organic synthesis, biochemistry, microbiology, structural biology, pharmacology, and animal models of infection. These studies will expand our knowledge in designing effective anti-MRSA compounds and understanding this new class of antibacterials.