Targeting cell separation systems of gram-negative bacteria.

描述（由申请人提供）：革兰氏阴性菌是多种重要人类疾病的病原体。这些生物体感染的成功治疗受到其周围复杂细胞包膜的阻碍。该包膜包括药物难以穿透的第二（外）膜层。因此，革兰氏阴性菌对抗生素具有高度的内在抗性，并且对许多对缺乏外膜的细菌有效的药物完全不敏感。在这个项目中，我们打算验证抗生素的新靶点，当灭活时，这些靶点会损害细胞外膜的渗透屏障。 膜以杀死革兰氏阴性细菌或消除其对批准的治疗剂的内在抗性。该项目是基于我们对大肠杆菌细胞分裂的研究。在这种革兰氏阴性细菌模型中，我们最近确定了分裂过程中细胞包膜重塑所需的因子，并开发了研究它们的工具。在分裂过程中，由细胞动力学机制产生的新细胞壁物质必须通过水解酶进行处理，以便子细胞分离。我们已经发现，这种加工是由称为酰胺酶的酶进行的，酰胺酶被具有LytM结构域的因子激活。一旦细胞壁被处理，第二组因子称为Tol-Glycoprotein系统催化外膜的收缩以完成分裂过程。对E.大肠杆菌和其他革兰氏阴性细菌导致形成长链的细胞，不能分离。这些细胞链已被证明具有受损的外膜渗透屏障，并且对许多药物过敏。尽管它们在维持外膜渗透屏障中的作用，但这些细胞分离系统对耐药性的重要性尚未在有问题的革兰氏阴性病原体中进行研究。因此，在这个项目中，我们将验证细胞分离系统作为潜在的药物靶标在病原体铜绿假单胞菌。分子遗传学将用于研究灭活这些系统对该生物体的生长和耐药性的影响，并将实施化学筛选以确定该过程的抑制剂。虽然我们专注于铜绿假单胞菌，但选择用于靶向的系统在革兰氏阴性细菌中高度保守。因此，我们的研究结果将广泛相关的革兰氏阴性菌感染的新疗法的发展。

DESCRIPTION (provided by applicant): Gram-negative bacteria are the causative agents of a variety of important human diseases. Successful treatment of infections with these organisms is hampered by the complex cell envelope that surrounds them. This envelope includes a second (outer) membrane layer that is difficult for drugs to penetrate. Gram-negative bacteria thus have a high intrinsic resistance to antibiotics and are completely insensitive to many drugs that are effective against bacteria lacking an outer membrane. In this project, we intend to validate new targets for antibiotics that when inactivated will compromise the permeability barrier of the outer membrane to either kill gram-negative bacteria or eliminate their intrinsic resistance to approved therapeutics. The project is based on our studies of cell division in Escherichia coli. In this model gram-negative bacterium, we recently identified factors required for cell envelope remodeling during division and have developed tools to study them. During division, new cell wall material produced by the cytokinetic machinery must be processed by hydrolytic enzymes for daughter cells to separate. We have discovered that this processing is carried out by enzymes called amidases that are activated by factors with LytM domains. Once the cell wall is processed, a second set of factors called the Tol-Pal system catalyzes the constriction of the outer membrane to complete the division process. Inactivation of either the amidases or the Tol-Pal system in E. coli and other gram-negative bacteria leads to the formation of long chains of cells that cannot separate. These cell chains have been shown to have a compromised outer membrane permeability barrier and are hypersensitive to many drugs. Despite their role in maintaining the outer membrane permeability barrier, the importance of these cell separation systems for drug resistance has not been investigated in problematic gram-negative pathogens. Therefore, in this project, we will validate cell separation systems as potential drug targets in te pathogen Pseudomonas aeruginosa. Molecular genetics will be used to investigate the effect of inactivating these systems on the growth and drug resistance of this organism, and chemical screens will be implemented to identify inhibitors of the process. Although we focus on P. aeruginosa, the systems chosen for targeting are highly conserved in gram-negative bacteria. Thus, our results will be broadly relevant to the development of novel treatments for gram-negative infections.