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Contribution of ClpE to virulence of Streptococcus pneumoniae

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The ATP-dependent caseinolytic proteases (Clp) play a fundamental role in stress tolerance and virulence in many pathogenic bacteria. Although ClpE of Streptococcus pneumoniae is required for growth at high temperatures, little is known about the role of ClpE in pathogenesis. In this study, we observed that the virulence of the clpE mutant of S. pneumoniae strain D39 was strongly reduced in a mouse intraperitoneal infection model. The clpE mutant also showed substantially reduced adherence to the human lung epithelial carcinoma A549 cell line and human umbilical-vein-derived endothelial cells. The underlying mechanism of virulence attenuation induced by the mutation of clpE was further investigated with real-time RT-PCR and 2-dimensional protein gel analysis. The results indicate that ClpE affects pneumococcal pathogenesis by modulating the expression of some important virulence determinants and metabolism-related factors in S. pneumoniae.

Les protéases caséinolytiques dépendantes de l’ATP (Clp) jouent un rôle fondamental dans la tolérance au stress et la virulence de plusieurs bactéries pathogènes. Même si ClpE de Streptococcus pneumoniae est requis à sa croissance à haute température, on sait peu de choses sur son rôle dans la pathogenèse. Dans cette étude, nous avons observé que la virulence du mutant clpE de S. pneumoniae (souche D39) était fortement réduite dans un modèle d’infection péritonéale chez la souris. L’adhérence du mutant cplE aux cellules de carcinome pulmonaire humain A549 et aux cellules endothéliales dérivées du cordon ombilical humain était aussi fortement réduite. Le mécanisme sous-jacent d’atténuation de la virulence induite par la mutation de clpE a été davantage examiné par RT-PCR en temps réel et par électrophorèse sur gel en 2 dimensions. Les résultats indiquent que ClpE affecte la pathogenèse du pneumocoque en modulant l’expression de quelques déterminants de virulence importants et de facteurs reliés au métabolisme chez S. pneumoniae.

Document Type: Research Article

Publication date: 2009-10-01

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  • Published since 1954, this monthly journal contains new research in the field of microbiology including applied microbiology and biotechnology; microbial structure and function; fungi and other eucaryotic protists; infection and immunity; microbial ecology; physiology, metabolism and enzymology; and virology, genetics, and molecular biology. It also publishes review articles and notes on an occasional basis, contributed by recognized scientists worldwide.
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