A novel pathway altering OM permeability

项目总结 革兰氏阴性外膜(OM)代表着一种强大的通透性屏障，它阻碍了 很多抗生素。截至目前，美国疾病控制和预防中心列出的大多数物种 “紧急的”或“严重的”对抗生素耐药性的担忧是革兰氏阴性的，部分原因是 奥姆。近年来，已经清楚地表明，OM的通透性可以通过生理上的 单元的状态。具体地说，与临床相关的压力，如营养限制，可能会导致 OM渗透性屏障，进一步减少抗生素的进入。对相关途径的解释 因为这种加强将导致开发能够削弱OM的小分子的新靶点 渗透性屏障。该实验室的长期目标是了解改变 在临床相关的应激期内OM的通透性。 具体地说，这个项目旨在阐明DNA错配修复丢失(MMR)和 大肠杆菌K12中OM通透性的变化MMR是一种高度保守的DNA修复机制 遍及生活的各个领域。在临床耐药菌株中发现了MMR突变株，并已 被认为是抗药性突变发展的前驱因素，这是由增加的 突变率。然而，初步数据表明，MMR的丢失会导致抗性的第二种途径 通过改变OM的通透性而对多种抗生素产生影响。因此，主机环境中的MMR丢失 将允许细菌在抗生素治疗中存活更长时间，同时也增加了一种特定的 由于突变率的增加，可能会产生抗药性突变。SOS DNA损伤应激反应 途径不是增强OM通透性屏障所必需的证明一种新的途径 将MMR损耗与OM通透性联系起来。 这项工作的中心假设是MMR的丢失激活了一条新的涉及信号转导和 改变OM通透性的转录变化。这个项目将阐明涉及到 通过识别途径激活导致OM改变所导致的转录变化来实现该途径 通透性(目标1)和确定通透性改变途径所必需的基因 (目标2)。这些目标的完成将改变人们对DNA修复和OM之间联系的理解 这种药物具有渗透性，有可能发现药物发现的新靶点。

PROJECT SUMMARY The gram-negative outer membrane (OM) represents a strong permeability barrier that impedes the entry of many antibiotics. The majority of the species the US Centers for Disease Control and Prevention list as of “urgent” or “serious” concern for antibiotic resistance are gram-negative in part due to the impermeability of the OM. In recent years, it has become clear that the permeability of the OM can be altered by the physiological state of the cell. Specifically, clinically relevant stresses such as nutrient limitation can result in strengthening of the OM permeability barrier, further decreasing the entry of antibiotics. Elucidation of the pathways responsible for this strengthening will lead to new targets for the development of small molecules that can weaken the OM permeability barrier. The laboratory’s long-term goal is to understand the mechanisms that change the permeability of the OM during periods of clinically relevant stress. Specifically, this project aims to elucidate a novel link between loss of DNA mismatch repair (MMR) and alteration of OM permeability in Escherichia coli K12. MMR is a highly conserved DNA repair mechanism found throughout all domains of life. MMR mutants have been found in clinical antibiotic resistant strains and have been proposed to be an antecedent to the development of resistance mutations facilitated by an increased mutation rate. However, preliminary data demonstrate a second pathway where loss of MMR leads to resistance to a broad range of antibiotics through alteration of OM permeability. Thus, loss of MMR in a host environment would allow bacteria to survive antibiotics treatment longer, while also increasing the probability that a specific resistance mutation can develop due to the increased mutation rate. The SOS DNA damage stress response pathway is not necessary for strengthening the OM permeability barrier demonstrating that a novel pathway connects loss of MMR to OM permeability. The central hypothesis of this work is loss of MMR activates a novel pathway involving signal transduction and transcriptional changes that alter the permeability profile of the OM. This project will elucidate genes involved in this pathway by identifying transcriptional changes that result from pathway activation leading to altered OM permeability (Aim 1) and determining the genes that are necessary for the pathway to altered OM permeability (Aim 2). Completion of the aims will transform understanding of the link between DNA repair and OM permeability and has the potential to uncover new targets for drug discovery.