Bile acids are prominent host and microbiota metabolites that modulate host immunity and microbial pathogenesis. However, the mechanisms by which bile acids suppress microbial virulence are not clear. To identify the direct protein targets of bile acids in bacterial pathogens, we performed activity-guided chemical proteomic studies. In Salmonella enterica serovar Typhimurium, chenodeoxycholic acid (CDCA) most effectively inhibited the expression of virulence genes and invasion of epithelial cells and interacted with many proteins. Notably, we discovered that CDCA can directly bind and inhibit the function of HilD, an important transcriptional regulator of S. Typhimurium virulence and pathogenesis. Our characterization of bile acid-resistant HilD mutants in vitro and in S. Typhimurium infection models suggests that HilD is one of the key protein targets of anti-infective bile acids. This study highlights the utility of chemical proteomics to identify the direct protein targets of microbiota metabolites for mechanistic studies in bacterial pathogens.

胆汁酸是重要的宿主和微生物代谢物，可调节宿主免疫和微生物发病机制。然而，胆汁酸抑制微生物毒力的机制尚不清楚。为了确定细菌病原体中胆汁酸的直接蛋白质靶标，我们进行了活性引导的化学蛋白质组学研究。在鼠伤寒沙门氏菌中，鹅去氧胆酸（CDCA）最有效地抑制毒力基因的表达和上皮细胞的侵袭，并与许多蛋白质相互作用。值得注意的是，我们发现CDCA可以直接结合并抑制HilD的功能，HilD是S.的重要转录调节因子。鼠伤寒杆菌毒力和发病机制。我们对体外和S中耐胆汁酸 HilD 突变体的表征。鼠伤寒感染模型表明 HilD 是抗感染胆汁酸的关键蛋白靶标之一。这项研究强调了化学蛋白质组学在识别微生物代谢物的直接蛋白质靶标方面的实用性，以用于细菌病原体的机制研究。