Temporal Regulation of a Salmonella Typhimurium Virulence Factor by the Transcriptional Regulator YdcR

• Published in: Molecular & cellular proteomics Vol. 16; no. 9; pp. 1683 - 1693
• Main Authors: Liu, Yanhua, Liu, Qian, Qi, Linlu, Ding, Tao, Wang, Zhen, Fu, Jiaqi, Hu, Mo, Li, Min, Song, Jeongmin, Liu, Xiaoyun
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2017; American Society for Biochemistry and Molecular Biology; The American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Animals; Bacteria; Bacterial infections; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Binding Sites; Conserved Sequence; Disease Models, Animal; Epithelial Cells - microbiology; Epithelial Cells - pathology; Galactosidase; Gene Expression Regulation, Bacterial; Genetics; Immunoblotting; Infections; Metabolism; Mice; Pathogenesis; Promoter Regions, Genetic - genetics; Protein Binding; Proteins; Proteomics; Salmonella; Salmonella Infections - metabolism; Salmonella Infections - microbiology; Salmonella Infections - pathology; Salmonella typhimurium - genetics; Salmonella typhimurium - pathogenicity; Time Factors; Transcription activation; Transcription factors; Transcription Factors - chemistry; Transcription Factors - metabolism; Transcription, Genetic; Up-Regulation; Virulence; Virulence factors; Virulence Factors - metabolism; β-Galactosidase
• ISSN: 1535-9476; 1535-9484
• DOI: 10.1074/mcp.M117.068296

We previously examined Salmonella proteome within infected host cells and found differential expression of many proteins with defined functional roles such as metabolism or virulence. However, the precise roles of other altered proteins in Salmonella pathogenesis are largely unknown. A putative transcriptional regulator, YdcR, was highly induced intracellularly whereas barely expressed in vitro, implicating potential relevance to bacterial infection. To unveil its physiological functions, we exploited quantitative proteomics of intracellular Salmonella and found that genetic ablation of ydcR resulted in severe repression of SrfN, a known virulence factor. Immunoblotting, qRT-PCR, and β-galactosidase assays further demonstrate YdcR-dependent transcription and expression of srfN. Moreover, we found physical interaction of YdcR with the promoter region of srfN, suggesting direct activation of its transcription. Importantly, a Salmonella mutant lacking ydcR was markedly attenuated in a mouse model of infection. Our findings reveal that YdcR temporally regulates the virulence factor SrfN during infection, thus contributing to Salmonella pathogenesis. Our work also highlights the utility of combining quantitative proteomics and bacterial genetics for uncovering the functional roles of transcription factors and likely other uncharacterized proteins as well.