Variations in a master regulator affects Clostridioides difficile physiology and virulence

项目摘要 艰难梭菌是一种重要的医院病原体，已被归类为 CDC的“紧急威胁”抗生素的使用是C. 艰难梭菌相关疾病，因为它破坏了健康的保护性肠道植物群，使C. 很难在结肠定植C.艰难梭菌通过分泌毒素破坏宿主组织， 通过形成孢子传播。毒素编码基因tcdA和tcdB是一种 致病性位点，并正受tcdR。养分供应和其他 环境因素对C.很难CodY，一种在哺乳动物中发现的蛋白质， 许多革兰氏阳性细菌病原体，是调节主要代谢的重要因素 途径和毒力基因的表达对养分供应的反应。In C.艰难梭，CodY 通过与配体、GTP和支链氨基结合来感知细胞的营养状态 这种活性CodY随后抑制毒素基因 通过与tcdR的启动子结合并抑制其转录来调节转录。我们有 鉴定出流行性C.艰难梭菌菌株（R20291）携带点突变 将其第146位的酪氨酸残基改变为天冬酰胺（codYY146N）。以下 根据这一观察，我们在数据库中的搜索使我们在170多个基因组中找到了codYV58A等位基因。 不同的C.不同来源的艰难菌株。类似于Y146（在二聚体界面处），V58是 位于CodY的关键位置（ILV结合结构域），并可影响其活性。 初步数据表明，CodYY146 N和CodYV58 A与野生型CodY的不同之处在于它们的表达。 功能和活动。主调节器的任何活动变化都可以改变基因 在其控制下的网络。本探索性补助金申请中的拟议研究将 鉴定C.由于生产困难， CodYV58A或CodYY146N，并将在C.生理学和发病机制的复杂性。

PROJECT SUMMARY Clostridioides difficile is an important nosocomial pathogen that has been classified as an “urgent threat” by CDC. Antibiotic use is the primary risk factor for the development of C. difficile-associated disease because it disrupts healthy protective gut flora and enables C. difficile to colonize the colon. C. difficile damage host tissue by secreting toxins and disseminates by forming spores. The toxins encoding genes, tcdA, and tcdB are part of a pathogenicity locus and are positively regulated by tcdR. Nutrient availability and other environmental factors greatly influence toxin production in C. difficile. CodY, a protein found in many Gram-positive bacterial pathogens, is an important factor that regulates major metabolic pathways and virulence gene expression in response to nutrient availability. In C. difficile, CodY senses the nutritional status of the cell by binding to ligands, GTP, and branched-chain amino acids (Isoleucine, Leucine, and Valine-ILV), and this active CodY then represses toxin genes transcription by binding to the promoter of tcdR and repressing its transcription. We have identified that the codY gene in an epidemic C. difficile strain (R20291) carries a point mutation that changes its Tyrosine residue at the 146th position to an Asparagine (codYY146N). Following this observation, our search in the database leads us to the codYV58A allele in more than 170 different C. difficile strains of different origins. Similar to Y146 (at the dimer interface), V58 is located (ILV binding domain) at a crucial position in CodY and can influence its activity. Preliminary data indicated that CodYY146N and CodYV58A differ from wild-type CodY in their function and activity. Any change in the activity of a master regulator can alter the gene regulatory networks under its control. Proposed studies in this exploratory grant application will identify the readjusted gene regulatory networks in C. difficile because of the production CodYV58A or CodYY146N and will evaluate their effect in C. difficile physiology and pathogenesis.