Characteristics of RegR Gene in Streptococcus pyogenes
| Autor: | Cherng-shyang Chang, 張程翔 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 Streptococcus pyogenes is commonly associated with many severe human diseases. Although many virulence factors have been extensively studied in streptococcal infections, the regulation of virulence genes is poorly understood. To search for the gene(s) that regulate the virulence genes in S. pyogenes, agaD which show strong sequence similarity with phosphotransfer system-like genes was identified. Our previous results have demonstrated AgaD influences the expression of SPE B, an important virulence factor of S. pyogenes. At the down stream of agaD fragment, a putative 996-nucleotide gene encoding RegR was identified in S. pyogenes. By BLAST homology searching, RegR protein is a homolog of LacI/GalR transcriptional family. To study the function of RegR in S. pyogenes, the recombinant streptococcal RegR (rRegR) was cloned and purified with GST tag affinity chromatography. The purified protein was confirmed by Mass/mass analysis, and used to generate the polyclonal antibodies against rRegR. To identify the role of regR in the regulation of virulence genes in S. pyogenes, we constructed isogenic regR mutant using the integrational plasmid to disrupt the regR gene. We found only aga locus, but not other virulence genes, was highly transcribed in regR mutant. In biological- phenotypic analysis, hemolysis and adhesion ability were significantly decreased in regR mutant compared with those in wild-type strain. No difference was found on growth rate, survival in blood, resistance to oxygen stress, and protease activity between wild-type and regR mutant strain. The mortality and lesion size in BALB/c mice infected with wild type and regR mutant strain were not significantly different. However, the phenomenon of wound healing in regR mutant infected mice was better than that in wild-type strain. Altogether, our results demonstrated that RegR of S. pyogenes has the ability to repress the transcription of aga locus, increase hemolysin activity, enhance adhesion ability and affect the persistence of infection, but not influence the growth in vitro, survival in blood, resistance to oxygen stress, and lethality in infected mice. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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