Iron and Fur gene regulation by an opportunistic pathogen

One of the most important strategies by the host innate immune system is to restrict the access of pathogens to iron, an essential nutrient. The goal of this study was characterize the low-iron and Fur regulons of Aggregatibacter actinomycetemcomitans (Aa), an opportunistic pathogen that causes oral cavity and abscess infections. The low-iron regulon is the set of genes differentially expressed in response to iron restriction, and was characterized by high-throughput RNA-sequencing (RNA-seq) of Aa biofilms grown on rich and low-iron media. The Fur regulon is the set of genes controlled by the bacterial iron sensor Ferric Uptake Regulator (Fur), and was characterized by a combination of RNA-seq of an Aa fur- mutant, to identify genes both directly and indirectly controlled by Fur, and chromatin immunoprecipitation (ChIP)-sequencing of Fur in Aa grown in vitro and in vivo in murine abscesses, to identify genes directly controlled by Fur in laboratory and host environments.

宿主先天免疫系统最为重要的策略之一，便是限制病原体获取铁这种必需营养物质。本研究旨在表征伴放线放线杆菌（Aggregatibacter actinomycetemcomitans，Aa）的低铁调节子与Fur调节子，该菌是一种可引发口腔与脓肿感染的条件致病菌。低铁调节子指响应铁限制条件时差异表达的基因集合，其表征通过对富铁与低铁培养基中培养的Aa生物膜开展高通量RNA测序（RNA-seq）实现。Fur调节子指由细菌铁感应蛋白——铁摄取调节因子（Ferric Uptake Regulator，Fur）——调控的基因集合，其表征结合了两种实验手段：一是对Aa的fur基因突变株开展RNA-seq，以鉴定受Fur直接与间接调控的基因；二是分别对体外培养以及小鼠脓肿体内定植的Aa进行Fur的染色质免疫共沉淀测序（ChIP-seq），以此鉴定在实验室环境与宿主环境中受Fur直接调控的基因。