Molecular mechanisms of antibacterial CDI toxin activation

抗菌CDI毒素激活的分子机制

• 批准号: 9323493
• 负责人: Celia Goulding
• 金额: $ 30.99万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA BARBARA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9323493
• 关键词: Active Sites; Affinity; Anti-Bacterial Agents; Bacteria; Bacterial Genome; Binding; Biochemical; Biochemical Genetics; C-terminal; Calcium; Catalysis; Cell surface; Cells; Complex; Cysteine Synthase; Data; Ecology; Elongation Factor; Escherichia coli; Evolution; Family; Genes; Genetic; Goals; Gram-Negative Bacteria; Growth; Human; Immunity; Mediating; Membrane Proteins; Modeling; Molecular; Molecular Genetics; Mutation; Pathway interactions; Peptide Elongation Factor Tu; Physiological; Protein Family; Protein Secretion; Proteins; Research; Resistance; Resolution; Ribonucleases; Role; Site-Directed Mutagenesis; Structure; Surveys; System; Testing; Toxin; Transfer RNA; Uropathogenic E. coli; anticodon nuclease; antimicrobial; biophysical techniques; genetic approach; in vitro activity; insight; microbial community; novel; novel strategies; pathogen; permissiveness; protein function; protein protein interaction; receptor

Project summary Bacteria have evolved complex strategies to compete and communicate with one another. One important mechanism of inter-bacterial competition is contact-dependent growth inhibition (CDI). CDI systems are found in a wide variety of Gram-negative bacteria, including many important human pathogens. CDI is mediated by the CdiB/CdiA family of two-partner secretion proteins. CdiB is an Omp85 outer-membrane protein that is required for the export and assembly of the CdiA exoprotein onto the cell surface. CdiA binds to receptors on susceptible bacteria and then delivers its C-terminal toxin domain (CdiA-CT) into the target cell. These systems also encode CdiI immunity proteins, which specifically bind to the CdiA-CT and neutralize toxin activity to protect CDI+ cells from auto-inhibition. CdiA-CT/CdiI sequences are highly variable, with >60 distinct toxin/immunity protein families recognized in bacterial genomes. We recently discovered that several CDI toxin/immunity proteins form higher order complexes with other cellular proteins. We hypothesize that these cellular protein function as "permissive" factors to activate CDI toxins inside target bacteria. The molecular mechanisms of CDI toxin activation are poorly understood, as are the broader physiological implications of toxin/permissive factor complexes. This application proposes a combination of genetic, biochemical and biophysical approaches to gain mechanistic insight into the network of protein-protein interactions that govern CDI. This research will significantly increase our understanding of the ecology and evolution of bacterial pathogens and could inform novel strategies for antimicrobial therapy.

项目概要 细菌已经进化出复杂的策略来相互竞争和交流。一 细菌间竞争的重要机制是接触依赖性生长抑制（CDI）。 CDI系统 存在于多种革兰氏阴性细菌中，包括许多重要的人类病原体。 CDI 是 由二伙伴分泌蛋白的 CdiB/CdiA 家族介导。 CdiB 是 Omp85 外膜 CdiA 外蛋白输出和组装到细胞表面所需的蛋白质。 CdiA 结合 敏感细菌上的受体，然后将其 C 末端毒素结构域 (CdiA-CT) 传递到靶细胞中。 这些系统还编码 CdiI 免疫蛋白，该蛋白特异性结合 CdiA-CT 并中和毒素 保护 CDI+ 细胞免受自身抑制的活性。 CdiA-CT/CdiI 序列高度可变，有 >60 个不同的序列 细菌基因组中识别的毒素/免疫蛋白家族。我们最近发现一些 CDI 毒素/免疫蛋白与其他细胞蛋白形成高级复合物。我们假设这些 细胞蛋白作为激活目标细菌内 CDI 毒素的“许可”因子。分子 人们对 CDI 毒素激活的机制知之甚少，更广泛的生理学意义也知之甚少。 毒素/许可因子复合物。该应用提出了遗传、生化和 生物物理学方法获得对控制蛋白质-蛋白质相互作用网络的机制洞察 CDI。这项研究将显着增加我们对细菌生态和进化的理解 病原体，并可以为抗菌治疗的新策略提供信息。