Molecular Mechanisms of Staphylococcus Epidermidis Strain Diversity

项目摘要/摘要 表皮葡萄球菌是人体皮肤和粘膜微生物区系中普遍存在的一种微生物。在功能上，它 通过免疫调节和微生物群落动态平衡对人类健康做出关键贡献。然而， ‘共生’表皮葡萄球菌也是一种重要的病原体和疾病风险储存库--它是最常见的 医疗器械和血液感染的原因。多个系统发育不同的亚种或品系， 表皮葡萄球菌可以与基因含量可变的基因组共生在皮肤上。绝大多数人 这些基因具有未知的功能。我们假设这种可变的基因含量，或附属基因组， 与核心基因相互作用，使菌株能够在不同的环境中做出独特的反应并茁壮成长，而且 混合这些遗传上不同的菌株对于维持皮肤的健康动态平衡是必要的。至 研究这些基因的功能，并了解菌株水平的遗传多样性如何有助于 种群水平的表型，我们将从功能上描述一组分离自 健康的个人和患有血液感染的个人。我们将为基因创建CRISPRi工具 在表皮葡萄球菌中进行敲除，以系统地识别菌株特异性和核心基因，这些基因构成了 在皮肤和感染中定居和竞争。AIM 1开发CRISPRi遗传工具包以创建池 表皮草击倒池。对这些池进行表型分析将极大地扩展我们对 共同微生物伙伴采用的重要共生策略，以及遗传异质性 可能会影响从共生到传染性的转变。目的2研究菌种混合物在这方面的作用 过渡。这种基因组方法和机制研究的结合将提供第一个研究 研究表皮葡萄球菌泛菌体的功能。诠释菌株间的遗传多样性将揭示新的 对菌株多样性的功能后果的洞察：菌株如何成功地在 共生和致病的生活方式，以及多种菌株如何在生态网络中共存。

PROJECT SUMMARY / ABSTRACT Staphylococcus epidermidis is a ubiquitous member of the human skin and mucosal microbiota. Functionally, it is a key contributor to human health via immune modulation and microbial community homeostasis. Yet the ‘commensal’ S. epidermidis is also an important pathogen and disease risk reservoir—it is the most frequent cause of medical device and bloodstream infections. Multiple phylogenetically diverse subspecies, or strains, of S. epidermidis can co-inhabit the skin with genomes of variable gene content. The overwhelming majority of these genes have unknown function. We hypothesize that this variable gene content, or accessory genome, interacts with core genes to enable strains to uniquely respond to and thrive in different environments, and that mixing of these genetically diverse strains is necessary to maintain a healthy homeostasis in the skin. To investigate the function of these genes and to understand how genetic diversity at the strain level contributes to population-level phenotype, we will functionally profile a set of phylogenetically diverse strains isolated from healthy individuals and individuals with bloodstream infections. We will create CRISPRi tools for gene knockdown in S. epidermidis to systematically identify strain-specific and core genes that underlie the ability to colonize and compete in the skin and infections. Aim 1 develops the CRISPRi genetic toolkit to created pooled S. epidermidis knockdown pools. Phenotypic profiling these pools will greatly expand our knowledge of important commensal strategies employed by a common microbial partner, and how genetic heterogeneity may impact the commensal to infectious transition. Aim 2 investigates the role of strain admixture in this transition. This combination of genomic approaches and mechanistic studies will provide the first investigation into the function of the S. epidermidis pangenome. Annotating inter-strain genetic diversity will reveal new insights into the functional consequence of strain diversity: how strains can successfully transition between commensal and virulence lifestyles, and how multiple strains can co-exist in an ecological network.