Biochemistry of Bacterial Cell Membranes

细菌细胞膜的生物化学

• 批准号: 7162517
• 负责人: HIROSHI NIKAIDO
• 金额: $ 65.34万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 1976
• 资助国家: 美国
• 起止时间: 1976-03-01 至 2011-01-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7162517
• 关键词: Address; Aminoglycosides; Antibiotics; Area; Biochemical; Biochemistry; Biological Assay; Cell Membrane Permeability; Cell membrane; Cell surface; Cells; Charge; Class; Clinical; Complex; Condition; Development; Escherichia coli; Family; Future; Gram-Negative Bacteria; Health; Human; Laboratories; Lead; Lipopolysaccharides; Measurement; Measures; Mediating; Membrane; Molecular; Molecular Genetics; Multi-Drug Resistance; Mutation; Numbers; Organism; Pathway interactions; Penetration; Permeability; Pharmaceutical Preparations; Phase; Phospholipids; Play; Prevalence; Prevention; Process; Property; Pump; Range; Resistance; Role; Source; Stress; Structure; Substrate Specificity; Thinking; Time; Work; antimicrobial; antimicrobial drug; cell envelope; clinically relevant; efflux pump; member; novel; pathogenic bacteria; porin; prevent; prototype; small molecule; solute

DESCRIPTION (provided by applicant): The increasing prevalence of multiple drug resistance in pathogenic bacteria is a major threat to human health. Especially Gram-negative bacteria are often intrinsically resistant to a number of antimicrobial agents, and such intrinsic resistance may easily become increased by common mutations. Studies in our and other laboratories in recent years led to the conclusion that such resistance is frequently mediated by mechanisms preventing the access of agents to their targets inside bacterial cells. Two "barriers" work in a truly synergistic manner. First, the Gram-negative outer membrane greatly retards the entry of antimicrobial agents, both hydrophilic and lipophilic, because the narrowness or paucity of porin channels makes the entry of hydrophilic agents difficult, and because the lipopolysaccharide-phospholipid asymmetric bilayer of this membrane slows down drastically the entry of lipophilic agents. Second, a few molecules of antibiotics that succeed in crossing the outer membrane are actively pumped out by ubiquitous multidrug efflux pumps that often show an incredibly wide substrate specificity. The pumps are frequently overproduced in the multidrug- resistant strains from clinical sources; this mechanism is especially troublesome because the use of a single drug can lead to simultaneous resistance to most of the existing antibiotics. We will continue to study both phases of the access-prevention mechanism. In the area of outer membrane permeability, we will study the mechanism whereby some porins are folded to produce only a few open channels. We will also study the molecular mechanism which makes the lipopolysaccharide-phospholipid bilayer so exceptionally impermeable, and will measure, for the first time, the entry of aminoglycosides across the outer membrane. In the area of multidrug efflux pumps, we will continue our studies of the structure and function of the major multidrug efflux pump of Escherichia coli, AcrAB-TolC, to understand why this transporter can handle such a wide range of compounds. The results of these studies will be very useful for the development of synthetic and semisynthetic antimicrobial compounds in the future.

描述（由申请方提供）：病原菌多重耐药性的日益普遍是对人类健康的主要威胁。特别是革兰氏阴性菌通常对许多抗微生物剂具有内在抗性，并且这种内在抗性可以容易地通过常见突变而增加。近年来我们和其他实验室的研究得出的结论是，这种耐药性通常是由阻止药剂进入细菌细胞内靶标的机制介导的。两个“屏障”以真正协同的方式发挥作用。首先，革兰氏阴性外膜极大地阻碍了亲水性和亲脂性抗微生物剂的进入，因为孔蛋白通道的狭窄或缺乏使得亲水性试剂难以进入，并且因为该膜的脂多糖-磷脂不对称双层大大减缓了亲脂性试剂的进入。其次，一些成功穿过外膜的抗生素分子被普遍存在的多药外排泵主动泵出，这些泵通常显示出令人难以置信的广泛底物特异性。在来自临床来源的多药耐药菌株中，泵经常过度产生;这种机制特别麻烦，因为使用单一药物可能导致对大多数现有抗生素的同时耐药性。我们将继续研究防止进入机制的两个阶段。在外膜渗透性方面，我们将研究一些孔蛋白被折叠而只产生少数开放通道的机制。我们还将研究使脂多糖磷脂双层如此异常不渗透的分子机制，并将首次测量氨基糖苷类药物穿过外膜的进入。在多药外排泵领域，我们将继续研究大肠杆菌主要多药外排泵AcrAB-TolC的结构和功能，以了解为什么这种转运蛋白可以处理如此广泛的化合物。这些研究结果将是非常有用的合成和半合成抗菌化合物在未来的发展。