Bacterial antibiotic resistance: structure, mechanism and inhibition of ABC transporters responsible for drug efflux and cell wall biogenesis.

细菌性疾病在世界各地造成了可怕的痛苦和死亡负担，但在过去的70年里，抗生素保护了我们免受最坏的影响。然而，我们现在面临着严重的危险，正如最近的首席医疗官Dame Sally Davies教授所说，抗生素耐药性的发展可能会“在气候变化之前杀死我们”。耐药性的增加可能会使现代医疗保健回到抗生素出现之前的时代，在这个时代，轻微的感染会危及生命，即使是常规的外科手术也有很大的风险。世界卫生组织在全球范围内都承认了这一问题的严重性，该组织已经发起了协调一致的努力来应对这一全球紧急情况，如果不加以控制，将导致数百万人过早死亡。像大肠杆菌和沙门氏菌这样的细菌被由两层脂膜组成的复杂细胞膜所包围，这为许多抗生素的进入提供了强大的屏障。对抗生素的抗药性是由专门的膜机制进一步建立的，这些机制识别抗生素，并在抗生素有机会发挥作用之前将它们从细胞中排出。这些药物外排泵由三个独立的组件组成：内部转运蛋白(存在三个不同的类别)，它识别药物并将药物传递到细胞外部开放的TolC“垃圾槽”，以及控制这种分子机器组装的关键适配器蛋白。我们的实验室已经建立了30多年的研究计划，研究细菌表现出抗生素耐药性的分子机制。我们已经成功地描述了TolC出口管的原子结构和作用，以及接头蛋白。我们还从原子角度定义了它们之间的相互作用，以及最广泛使用的这类外排泵中的传送器组件。这最终导致了第一个完整组装的多药外排泵的精确原子视图，提供了对它如何打开以允许排出以及如何抑制这一点的洞察。最近，我们描述了泵的一个以前没有特征的运输器组件的结构，揭示了一种新的结构和药物外排的非典型机制。一种与伴侣蛋白协同作用的相关但不同的转运蛋白使用相同的结构将脂蛋白--保护细胞膜的关键成分--运输到外膜。如果这个系统没有正常运行，细菌就不能生存，这使它成为治疗干预的一个有吸引力的目标。我们寻求继续为我们的工作提供资金，以研究药物外排和脂蛋白运输中的这些相关转运蛋白。通过了解他们如何识别他们运输的分子以及如何与他们的伴侣蛋白质相互作用，我们将更好地理解细菌抵抗抗生素的分子机制，并提高对抗它们的可能性。

Bacterial diseases impose a terrible burden of suffering and death throughout the world but for the past 70 years antibiotics have shielded us from the worst. However, we now face serious peril as the development of antibiotic resistance may, in the words of recent Chief Medical Officer Professor Dame Sally Davies, "kill us before climate change." Increased resistance threatens to revert modern healthcare to a pre-antibiotic era where minor infections become life threatening and even routine surgical procedures carry significant risk. The severity of the problem is acknowledged globally by the World Health Organization, which has initiated coordinated efforts to address this global emergency, which unchecked will lead to millions of premature deaths.Bacteria like E. coli and Salmonella are surrounded by a complex cell envelope consisting of two lipid membranes, which provides a formidable barrier to the entry of many antibiotics. Resistance to antibiotics is further established by dedicated membrane machineries that recognise antibiotics and eject them from the cell before they have an opportunity to act. These drug efflux pumps are composed of three separate components: an inner transporter protein (of which three different classes exist) which recognizes and passes drugs to a TolC "trash chute" open to the cell exterior, and a critical adaptor protein which controls the assembly of this molecular machine.Our laboratory has over 30 years built a research program tackling the molecular mechanisms by which bacteria exhibit antibiotic resistance. We have succeeded in describing the atomic structure and action of the TolC exit duct, and the adaptor proteins. We have also atomically defined their interactions with each other, and the transporter component in the most widespread class of these efflux pumps. This culminated in the first precise atomic view of a complete assembled multidrug efflux pump, provided insight into how it opens to allow expulsion, and how this might be inhibited. More recently, we described the structure of a previously uncharacterised transporter component of a pump revealing a novel structure and atypical mechanism of drug efflux. A related, but distinct, transporter acting in concert with chaperone proteins uses the same architecture to transport lipoproteins, vital components of the protective cell envelope, to the outer membrane. Without this system functioning properly, bacteria cannot survive, making it an attractive target for therapeutic intervention. We seek a continuation of funding for our work, to study these related transporters in drug efflux and lipoprotein transport. By understanding how they recognise the molecules they transport and interact with their partner proteins we will develop a better understanding of the molecular mechanisms by which bacteria resist antibiotics and raise the possibility of counteracting them.