Class A Carbapenemases

描述(申请人提供)：A类碳青霉烯酶与其他耐药机制相结合，能够对几乎所有可用的抗生素产生耐药性，并对威胁生命的感染的成功治疗构成非常严重的挑战。KPC和GES型碳青霉烯酶广泛分布于世界各地分离的各种革兰氏阴性病原菌中，具有特殊的临床意义。缺乏关于这些酶与碳青霉烯类抗生素相互作用的详细的稳态前动力学研究和结构信息，是阐明这些有害细菌酶的作用机制(S)的主要障碍。我们的研究将为合理设计下一代β-内酰胺类抗生素和A类碳青霉烯酶抑制剂提供结构和力学基础。我们研究的长期目标是描绘A类碳青霉烯酶的详细动力学，并阐明这些酶的结构及其与碳青霉烯类抗生素的相互作用。本申请的目的是通过追求三个具体目标对A类碳青霉烯酶进行详细的研究：1)进行临床上重要的A类碳青霉烯酶的结构和动力学研究；2)进行新型A类碳青霉烯酶的研究；以及3)阐明A类碳青霉烯酶活性进化的途径。为了阐明这些临床上重要的抗生素耐药酶的机制，我们将利用多学科的方法，包括分子生物学、蛋白质化学、详细的酶学、质谱学和X射线结晶学，研究天然酶及其与四种临床使用的碳青霉烯类抗生素的复合体。阐明最终导致A-内酰胺酶获得碳青霉烯酶活力的结构和动力学机制将有助于我们理解这些临床上重要的酶的进化潜力，并将为碳青霉烯类抗生素的未来应用提供重要的指导。碳青霉烯是治疗危及生命的感染的最后手段。

DESCRIPTION (provided by applicant): Class A carbapenemases in combination with other resistance mechanisms are capable of producing resistance to virtually all available antibiotics and pose a very serious challenge for the successful treatment of life-threatening infections. The KPC- and GES-type carbapenemases are of a special clinical concern as they are widely distributed in various Gram-negative pathogens, isolated from different parts of the world. Lack of a detailed pre-steady-state kinetic studies and structural information regarding interaction of these enzymes with carbapenem antibiotics constitutes the major impediment for elucidation of mechanism(s) of these deleterious bacterial enzymes. Our studies would provide structural and mechanistic basis for rational design of the future generations of ?-lactam antibiotics and inhibitors of class A carbapenemases. The long-term goal of our studies is to delineate detailed kinetics of class A carbapenemases and elucidate structures of these enzymes and their interactions with carbapenem antibiotics. The objectives in this application is to conduct detailed studies of class A carbapenemases by pursuing three Specific Aims: 1) Perform structural and kinetic studies of clinically important class A carbapenemases; 2) Perform studies of novel class A carbapenemases; and 3) Elucidate pathways for evolution of carbapenemase activity in class A ?-lactamases. To elucidate the mechanistic aspects of these clinically important antibiotic-resistance enzymes, we will utilize a multidisciplinary approach that includes molecular biology, protein chemistry, detailed enzymology, mass spectrometry, and X-ray crystallography of the native enzymes and their complexes with four clinically used carbapenem antibiotics. Elucidation of structural and kinetic mechanisms that ultimately resulted in acquisition of carbapenemase activity by class A ?-lactamases would greatly contribute to our understanding of the evolutionary potential of these clinically important enzymes and would provide an important guidance for the future utility of carbapenems, antibiotics of the last resort for treatment of life-threatening infections.