This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Google Scholar
Right arrow Articles by Abi Khattar, Z.
Right arrow Articles by Gaudriault, S.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Abi Khattar, Z.
Right arrow Articles by Gaudriault, S.

 Previous Article  |  Next Article 

Journal of Bacteriology, November 2009, p. 7063-7073, Vol. 191, No. 22
0021-9193/09/$08.00+0     doi:10.1128/JB.00892-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

The dlt Operon of Bacillus cereus Is Required for Resistance to Cationic Antimicrobial Peptides and for Virulence in Insects{triangledown}

Z. Abi Khattar,1,2,3 A. Rejasse,4 D. Destoumieux-Garzón,5 J. M. Escoubas,1,2 V. Sanchis,4 D. Lereclus,4 A. Givaudan,1,2 M. Kallassy,3 C. Nielsen-Leroux,4 and S. Gaudriault1,2*

INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France,1 Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France,2 Laboratoire de Biotechnologie, Faculté des Sciences, Université Saint-Joseph de Beyrouth, BP 11-514 Riad el Solh, Beirut 1107 2050, Lebanon,3 Unité Génétique Microbienne et Environnement, Institut National de la Recherche Agronomique, La Minière, 78285 Guyancourt Cedex, France,4 CNRS, Ifremer, IRD, Université Montpellier 2, UMR 5119, Ecosystèmes Lagunaires, Place E. Bataillon, CC80, 34095 Montpellier Cedex 5, France5

Received 9 July 2009/ Accepted 10 September 2009

The dlt operon encodes proteins that alanylate teichoic acids, the major components of cell walls of gram-positive bacteria. This generates a net positive charge on bacterial cell walls, repulsing positively charged molecules and conferring resistance to animal and human cationic antimicrobial peptides (AMPs) in gram-positive pathogenic bacteria. AMPs damage the bacterial membrane and are the most effective components of the humoral immune response against bacteria. We investigated the role of the dlt operon in insect virulence by inactivating this operon in Bacillus cereus, which is both an opportunistic human pathogen and an insect pathogen. The {Delta}dltBc mutant displayed several morphological alterations but grew at a rate similar to that for the wild-type strain. This mutant was less resistant to protamine and several bacterial cationic AMPs, such as nisin, polymyxin B, and colistin, in vitro. It was also less resistant to molecules from the insect humoral immune system, lysozyme, and cationic AMP cecropin B from Spodoptera frugiperda. {Delta}dltBc was as pathogenic as the wild-type strain in oral infections of Galleria mellonella but much less virulent when injected into the hemocoels of G. mellonella and Spodoptera littoralis. We detected the dlt operon in three gram-negative genera: Erwinia (Erwinia carotovora), Bordetella (Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica), and Photorhabdus (the entomopathogenic bacterium Photorhabdus luminescens TT01, the dlt operon of which did not restore cationic AMP resistance in {Delta}dltBc). We suggest that the dlt operon protects B. cereus against insect humoral immune mediators, including hemolymph cationic AMPs, and may be critical for the establishment of lethal septicemia in insects and in nosocomial infections in humans.

* Corresponding author. Mailing address: Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France. Phone: 33 4 67 14 48 12. Fax: 33 4 67 14 46 79. E-mail: sgaudriault{at}univ-montp2.fr

{triangledown} Published ahead of print on 18 September 2009.

Journal of Bacteriology, November 2009, p. 7063-7073, Vol. 191, No. 22
0021-9193/09/$08.00+0     doi:10.1128/JB.00892-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»