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Journal of Bacteriology, July 2008, p. 4453-4459, Vol. 190, No. 13
0021-9193/08/$08.00+0     doi:10.1128/JB.00154-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Effect of Growth Temperature on Crl-Dependent Regulation of {sigma}S Activity in Salmonella enterica Serovar Typhimurium{triangledown}

Véronique Robbe-Saule, Ingrid Carreira,{dagger} Annie Kolb, and Françoise Norel*

Unité de Génétique moléculaire and CNRS URA2172, Institut Pasteur, Paris, France

Received 30 January 2008/ Accepted 22 April 2008

The small regulatory protein Crl favors association of the stationary-phase sigma factor {sigma}S (RpoS) with the core enzyme polymerase and thereby increases {sigma}S activity. Crl has a major physiological impact at low levels of {sigma}S. Here, we report that the Crl effects on {sigma}S-dependent gene expression, the H2O2 resistance of Salmonella enterica serovar Typhimurium, and the resistance of this organism to acidic pH are greater at 28°C than at 37°C. Immunoblot experiments revealed a negative correlation between {sigma}S and Crl levels; the production of Crl was slightly greater at 28°C than at 37°C, whereas the {sigma}S levels were about twofold lower at 28°C than at 37°C. At both temperatures, Crl was present in excess of {sigma}S, and increasing the Crl level further did not increase the H2O2 resistance level of Salmonella and the expression of the {sigma}S-dependent gene katE encoding the stationary-phase catalase. In contrast, increasing the {sigma}S level rendered Salmonella more resistant to H2O2 at 28°C, increased the expression of katE, and reduced the magnitude of Crl activation. In addition, the effect of Crl on katE transcription in vitro was not dependent on temperature. These results suggest that the effect of temperature on Crl-dependent regulation of the katE gene and H2O2 resistance are mediated mainly via an effect on {sigma}S levels. In addition, our results revealed that {sigma}S exerts a negative effect on the production of Crl in stationary phase when the cells contain high levels of {sigma}S.

* Corresponding author. Mailing address: Institut Pasteur, Unité de Génétique Moléculaire, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France. Phone: 33 140613122. Fax: 33 145688960. E-mail francoise.norel{at}pasteur.fr

{triangledown} Published ahead of print on 2 May 2008.

{dagger} Present address: Universidade Católica-Ecola Superior de Biotecnologia, Extensão de Caldas da Rainha, Rua Mestre Mateus Fernandes, 2500-237 Caldas da Rainha, Portugal.

Journal of Bacteriology, July 2008, p. 4453-4459, Vol. 190, No. 13
0021-9193/08/$08.00+0     doi:10.1128/JB.00154-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • England, P., Westblade, L. F., Karimova, G., Robbe-Saule, V., Norel, F., Kolb, A. (2008). Binding of the Unorthodox Transcription Activator, Crl, to the Components of the Transcription Machinery. J. Biol. Chem. 283: 33455-33464 [Abstract] [Full Text]  


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