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Infection and Immunity, May 2000, p. 2954-2961, Vol. 68, No. 5
Laboratoire de Pathologie Infectieuse et
Immunologie, Institut National de la Recherche Agronomique, Centre
de Recherches de Tours, 37380 Nouzilly, France
Received 17 September 1999/Returned for modification 17 November
1999/Accepted 20 January 2000
Brucella melitensis is a facultative intracellular
pathogen which is able to survive and replicate within phagocytic
cells. Therefore, it has to adapt to a range of different hostile
environments. In order to understand the mechanisms of intracellular
survival employed by virulent B. melitensis 16M, an initial
approach consisting of analysis of the differences in patterns of
protein synthesis in response to heat, oxidative, and acid pH stresses
by two-dimensional (2-D) polyacrylamide gel electrophoresis was used.
Depending on the stress, this involved about 6.4 to 12% of the 676 protein spots detected in 2-D gel electrophoresis. On the basis of
N-terminal sequence analysis and database searching, 19 proteins whose
level of synthesis was up- or down-regulated by stress conditions were identified. Some of them were previously reported for
Brucella, such as BvrR, DnaK, GroEL, and Cu-Zn superoxide
dismutase (SOD). Eight other proteins closely matched proteins found in
other bacteria: AapJ, alpha-ETF, ClpP, Fe and/or Mn SOD, malate
dehydrogenase, IalB, 30S ribosomal protein S1, and pyruvate
dehydrogenase E1 component beta subunit. Results indicated that
B. melitensis could bring specific regulatory mechanisms
into play in response to stress conditions. For example, the ribosome
releasing factor in B. melitensis appeared to be a heat
shock protein, whereas the ClpP protein, described as a heat shock
protein for Escherichia coli, was strongly down-regulated
in B. melitensis in response to heat stress. Some of the
identified proteins and their potential specific regulation could be
required for the adaptation of B. melitensis to
environmental stresses encountered in phagocytic cells and possibly for
bacterial virulence.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Characterization of Heat, Oxidative, and Acid
Stress Responses in Brucella melitensis
*
Corresponding author. Mailing address: Laboratoire de
Pathologie Infectieuse et Immunologie, INRA, Centre de Recherches de Tours, 37380 Nouzilly, France. Phone: (33) 2 47 42 78 67. Fax: (33) 2 47 42 77 79. E-mail:
Ana-Paula.Teixeira{at}tours.inra.fr.
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