Relationship between virulence factor and toxin antitoxin system in enterococcus
Toxin-antitoxin system is a regulatory system where two sets of genes encodes the toxin and its corresponding antitoxin. There is no documented study that showed the association between virulence genes and TA system in Enterococcus faecium and Enterococcus faecalis. For this purpose,the prevalen...
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| Format: | Thèse |
| Langue: | English |
| Publié: |
2014
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| Accès en ligne: | http://ethesis.upm.edu.my/id/eprint/12700/1/FPSK%28M%29%202014%206%20T.pdf |
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| Résumé: | Toxin-antitoxin system is a regulatory system where two sets of genes
encodes the toxin and its corresponding antitoxin. There is no documented
study that showed the association between virulence genes and TA system in
Enterococcus faecium and Enterococcus faecalis.
For this purpose,the prevalence of TA systems in independently isolated
clinical isolates of E. faecium and E. faecalis were determined, then the
dominant TA systems were identified, different virulence genes in E. faecium
andE. faecalisare surveyed and subsequently the level of expression of
virulence and TA genes in normal and stress conditions were determined
and finally their association with TA genes are defined.Remarkably,
sequences for one particular TA pair, mazEFand higBATA systems, were
present on plasmid and chromosome of all E. faecium andE. faecalisstrains,
respectively. Additionally, toxin transcript expression levels were increased
when bacteria were grown under stressful conditions. The pilB, fms8, efaAfm
and sgrA are the most prevalent virulence genes in E. faecium andE. faecalis.
These virulence genes were reported for first time inE. Faecalis, so this study
demonstrated the importance of horizontal transformation in E. faecium
andE. Faecalis. Peptide nucleic acid assay demonstrated with silencing of
mazF by anti-mazF PNA a decrease of expression level of virulence genes
were observed. The findings showed association between TA systems and
virulence factor. The mazEF TA locion plasmidand higBA TA genes on
chromosome of all E. faecium andE. faecalis were dominant. Also, there was
decreasing of expression of virulence genes in presence of anti mazF-PNA.
Therefore, it is recommended that mazEF
TA systems are potent and sensitive targets in of all E. faecium and E.Faecalis.
Hence, deactivation of the toxin proteins in the mazEF TA system should be
investigated further as an effective antibacterial strategy against this
bacterium. |
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