The Leucine-Responsive Regulatory Protein is a global regulator involved in the virulence of Clostridium difficile

• Main Authors: Yi-ChingChiu, 邱意晴
• Other Authors: I-Hsiu Huang
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/h3na9q

碩士 === 國立成功大學 === 微生物及免疫學研究所 === 104 === Clostridium difficile is a spore-forming pathogen and leading cause of antibiotic-associated diarrhea. Most pathogenic strains secret toxin A (TcdA) and toxin B (TcdB), which are the primary virulence factors responsible for disease symptoms of C. difficile infections (CDI). Published studies have suggested the expression of tcdA and tcdB promoter is controlled by TcdR and TcdC, two transcriptional regulators located on C. difficile pathogenicity locus (PaLoc). Leucine-responsive regulatory protein (Lrp) is a global regulator which has been indicated to positively or negatively affect many metabolic associated operons in E. coli and B. subtilis. Since Lrp is considered to be a global regulator, we hypothesized that it also affects virulent genes including tcdA and tcdB. Interestingly, our results showed that there were more tcdA, tcdB, tcdR and tcdC expressed in the absence of Lrp when compared to the wild type. These results suggest that Lrp may play an important role in downregulating the expression of genes on the whole PaLoc. Furthermore, our results showed that Lrp might affect toxin production via controlling known regulators of toxin production, CcpA and CodY. In addition, we also found that disruption of lrp reduced spore formation in C. difficile. Finally, we investigated whether Lrp is involved in virulence in vivo and the results showed that lrp mutant was more virulent than wild type in murine model of infection. In summary, Lrp was identified for the first time in C. difficile and shown to participate in its virulent factors regulation, including toxin production and sporulation.