This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ibrahim, M. Articles by Monnet, V. Search for Related Content PubMed PubMed Citation Articles by Ibrahim, M. Articles by Monnet, V.

 Previous Article  |  Next Article 

Journal of Bacteriology, December 2007, p. 8844-8854, Vol. 189, No. 24
0021-9193/07/$08.00+0     doi:10.1128/JB.01057-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Control of the Transcription of a Short Gene Encoding a Cyclic Peptide in Streptococcus thermophilus: a New Quorum-Sensing System?

Mariam Ibrahim,¹ Alain Guillot,² Francoise Wessner,¹ Florence Algaron,¹ Colette Besset,¹ Pascal Courtin,¹ Rozenn Gardan,¹ and Véronique Monnet^1*

INRA, Unité de Biochimie Bactérienne, UR477, F-78350 Jouy en Josas, France,¹ INRA, PAPSS, F-78350 Jouy en Josas, France²

Received 5 July 2007/ Accepted 20 September 2007

Gram-positive bacteria secrete a variety of peptides that are often subjected to posttranslational modifications and that are either antimicrobials or pheromones involved in bacterial communication. Our objective was to identify peptides secreted by Streptococcus thermophilus, a nonpathogenic bacterium widely used in dairy technology in association with other bacteria, and to understand their potential roles in cell-cell communication. Using reverse-phase liquid chromatography, mass spectrometry, and Edman sequencing, we analyzed the culture supernatants of three S. thermophilus strains (CNRZ1066, LMG18311, and LMD-9) grown in a medium containing no peptides. We identified several peptides in the culture supernatants, some of them found with the three strains while others were specific to the LMD-9 strain. We focused our study on a new modified peptide secreted by S. thermophilus LMD-9 and designated Pep1357C. This peptide contains 9 amino acids and lost 2 Da in a posttranslational modification, most probably a dehydrogenation, leading to a linkage between the Lys2 and Trp6 residues. Production of Pep1357C and transcription of its encoding gene depend on both the medium composition and the growth phase. Furthermore, we demonstrated that transcription of the gene coding for Pep1357C is drastically decreased in mutants inactivated for the synthesis of a short hydrophobic peptide, a transcriptional regulator, or the oligopeptide transport system. Taken together, our results led us to deduce that the transcription of the Pep1357C-encoding gene is controlled by a new quorum-sensing system.

---

* Corresponding author. Mailing address: INRA, Unité de Biochimie Bactérienne, UR477, F-78350 Jouy en Josas, France. Phone: 33-1-34-65-21-49. Fax: 33-1-34-65-21-63. E-mail: veronique.monnet{at}jouy.inra.fr

Published ahead of print on 5 October 2007.

---

Journal of Bacteriology, December 2007, p. 8844-8854, Vol. 189, No. 24
0021-9193/07/$08.00+0     doi:10.1128/JB.01057-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Gardan, R., Besset, C., Guillot, A., Gitton, C., Monnet, V. (2009). The Oligopeptide Transport System Is Essential for the Development of Natural Competence in Streptococcus thermophilus Strain LMD-9. J. Bacteriol. 191: 4647-4655 [Abstract] [Full Text]  
• Giaouris, E., Briandet, R., Meyrand, M., Courtin, P., Chapot-Chartier, M.-P. (2008). Variations in the Degree of D-Alanylation of Teichoic Acids in Lactococcus lactis Alter Resistance to Cationic Antimicrobials but Have No Effect on Bacterial Surface Hydrophobicity and Charge. Appl. Environ. Microbiol. 74: 4764-4767 [Abstract] [Full Text]