title: CpsR, a GntR family regulator, transcriptionally regulates capsular polysaccharide biosynthesis and governs bacterial virulence in Streptococcus pneumoniae.
abstract: Transcriptional regulation of capsule expression is critical for pneumococcal transition from carriage to infection, yet the underlying mechanism remains incompletely understood. Here, we describe the regulation of capsular polysaccharide, one of the most important pneumococcal virulence factor by a GntR family regulator, CpsR. Electrophoretic mobility-shift assays have shown the direct interaction between CpsR and the cps promoter (cpsp), and their interaction could be competitively interfered by glucose. DNase I footprinting assays localized the binding site to a region -146 to -114 base pairs relative to the transcriptional start site of the cps locus in S. pneumoniae D39. We found that CpsR negatively controlled the transcription of the cps locus and hence CPS production, which was confirmed by fine-tuning expression of CpsR in a ΔcpsR complemented strain. Increased expression of CpsR in complemented strain led to a decreased resistance to the whole-blood-mediated killing, suggesting a protective role for CpsR-cpsp interaction in the establishment of invasive infection. Finally, animal experiments showed that CpsR-cpsp interaction was necessary for both pneumococcal colonization and invasive infection. Taken together, our results provide a thorough insight into the regulation of capsule production mediated by CpsR and its important roles in pneumococcal pathogenesis.
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, People's republic of China.
authors.forename: Kaifeng
authors.initials: K
authors.lastname: Wu
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, People's republic of China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Xu
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, People's republic of China.
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, People's republic of China.
authors.forename: Libin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, People's republic of China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Diagnostic Medicine designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, People's republic of China.
authors.forename: Yibing
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D001770:Blood Bactericidal Activity; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D008807:Mice, Inbred BALB C; D011008:Pneumococcal Infections / Q000382:microbiology / Q000473:pathology; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D016019:Survival Analysis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011135:Polysaccharides, Bacterial; D014157:Transcription Factors