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Journal of Bacteriology, November 2006, p. 7707-7710, Vol. 188, No. 21
0021-9193/06/$08.00+0 doi:10.1128/JB.00644-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
An RpoH-Like Heat Shock Sigma Factor Is Involved in Stress Response and Virulence in Brucella melitensis 16M
,
Marie Delory,
Régis Hallez,
Jean-Jacques Letesson, and
Xavier De Bolle*
Research Unit in Molecular Biology, University of Namur, Namur, Belgium
Received 5 May 2006/
Accepted 16 August 2006
B. melitensis 16M genome analysis revealed the presence of six putative sigma factor-encoding genes: rpoD, rpoH1, rpoH2, rpoE1, rpoE2, and rpoN. We mutated all these genes except rpoD. Phenotypic analysis of the mutants reveals that a strain carrying an rpoH2 null mutation (
rpoH2) is impaired for growth at 21 and 42°C and shows increased sensitivity to hydrogen peroxide. Compared to the wild-type strain, the
rpoH2 mutant is attenuated in all virulence models tested. Three other null mutants (
rpoH1,
rpoE1, and
rpoE2 mutants) are also defective for survival in mice at 4 weeks postinfection. We also demonstrated that rpoH2 deletion strongly reduces the expression of two major virulence factors in B. melitensis, the type IV secretion system and the flagellum.
* Corresponding author. Mailing address: Research Unit in Molecular Biology (URBM), University of Namur (FUNDP), 61 rue de Bruxelles, 5000 Namur, Belgium. Phone: 32 81 72 44 38. Fax: 32 81 72 42 97. E-mail:
xavier.debolle{at}fundp.ac.be.
Published ahead of print on 25 August 2006.
Supplemental material for this article may be found at http://jb.asm.org/.
Journal of Bacteriology, November 2006, p. 7707-7710, Vol. 188, No. 21
0021-9193/06/$08.00+0 doi:10.1128/JB.00644-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
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