PHASE VARIATION IN LISTERIA MONOCYTOGENES

单核细胞增生李斯特氏菌的相变

• 批准号: 6071191
• 负责人: Laurel L Lenz
• 金额: $ 3.24万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6071191
• 关键词: Listeria; bactericidal immunity; cell cycle; cytotoxic T lymphocyte; genetic strain; laboratory mouse; microorganism growth; tissue /cell culture; virulence

I propose to study a mechanism for regulation of reversible bacterial cell differentiation which L. monocytogenes exhibits both in vitro and in colonized animals. The studied differentiation step involves phase-variation in the completion of L. monocytogenes septation during cell-division, which manifests as smooth (S) or rough (R) colony morphologies. I will identify the lesion in a transposon mutagenized, R-phase-locked L. monocytogenes strain. The effect that expression of this disrupted locus (termed efs) has on L. monocytogenes morphology will be evaluated by studying the morphological consequences of efs deletion and overexpression. Subsequently, mutants locked in S-phase will be engineered by altering expression of the efs locus, or isolated in screens of mutagenized L. monocytogenes. These phase-locked strains will be used to study the effects of phase-variation on the ability of L. monocytogenes to compete for colonization of the gut and internal organs of orally and intravenously-infected mice. The phase-locked L. monocytogenes strains will also be used to evaluate the effects of phase-variation on development of host T cell immune responses to this pathogen. For this experiment, CTL responses to a subset of previously-defined peptide epitopes from bacterial proteins will be quantitated. The expression of these bacterial proteins is known to differ in S-phase and R-phase L. monocytogenes. The studies in this proposal should provide insight into a potentially novel mechanism for regulation of bacterial cell differentiation and will begin to address how this mechanism affects virulence and immunogenicity of L. monocytogenes in a murine host.

我建议研究单增李斯特菌在体外和定植动物中表现出的可逆细菌细胞分化的调节机制。 研究的分化步骤涉及细胞分裂过程中单增李斯特菌分隔完成的相变，表现为光滑（S）或粗糙（R）集落形态。 我将鉴定转座子诱变的 R 相锁定单核细胞增生李斯特菌菌株中的病变。 将通过研究 efs 缺失和过度表达的形态学后果来评估该破坏基因座（称为 efs）的表达对单核细胞增生利斯特氏菌形态的影响。 随后，锁定在 S 期的突变体将通过改变 efs 基因座的表达进行工程设计，或在诱变的单核细胞增生李斯特菌的筛选中分离。这些锁相菌株将用于研究相位变化对单核细胞增生利斯特氏菌在口服和静脉注射感染小鼠的肠道和内脏器官中竞争定植的能力的影响。 锁相单核细胞增生李斯特菌菌株还将用于评估相变对该病原体的宿主 T 细胞免疫反应的影响。 在本实验中，将对细菌蛋白中先前定义的肽表位子集的 CTL 反应进行定量。 已知这些细菌蛋白的表达在单核细胞增生李斯特菌的 S 期和 R 期有所不同。 该提案中的研究应提供对调节细菌细胞分化的潜在新机制的深入了解，并将开始解决该机制如何影响小鼠宿主中单核细胞增生李斯特氏菌的毒力和免疫原性。