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Infection and Immunity, July 2000, p. 3861-3866, Vol. 68, No. 7
Department of Zoology and Genetics, Iowa
State University, Ames, Iowa 50011
Received 10 December 1999/Returned for modification 17 February
2000/Accepted 30 March 2000
All aerobic organisms have mechanisms that protect against
oxidative compounds. Catalase, peroxidase, superoxide dismutase, glutathione, and thioredoxin are widely distributed in many taxa and
constitute elements of a nearly ubiquitous antioxidant metabolic strategy. Interestingly, the regulatory mechanisms that control these
elements are rather different depending on the nature of the oxidative
stress and the organism. Catalase is well documented to play an
important role in protecting cells from oxidative stress. In
particular, pathogenic bacteria seem to use this enzyme as a defensive
tool against attack by the host. To investigate the significance of
catalase in hostile environments, we made catalase deletion mutations
in two different B. abortus strains and used two-dimensional gel analysis, survival tests, and adaptation
experiments to explore the behavior and role of catalase under several
oxidative stress conditions. These studies show that B. abortus strains that do not express catalase activity exhibit
increased sensitivity to hydrogen peroxide. We also demonstrate that
catalase expression is regulated in this species, and that preexposure
to a sublethal concentration of hydrogen peroxide allows B. abortus to adapt so as to survive subsequent exposure to higher
concentrations of hydrogen peroxide.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Regulation of Brucella abortus
Catalase

and
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Corresponding author. Mailing address: Department of
Zoology and Genetics, 2106 Molecular Biology Building, Iowa State
University, Ames, IA 50011. Phone: (515) 294-1170. Fax: (515) 294-3003. E-mail: jemayf{at}iastate.edu.
Present address: Department of Ophthalmology and Visual Science,
College of Medicine, The Catholic University of Korea, and Catholic
Research Institute of Medical Sciences, 505 Banpo-dong, Seocho-ku,
Seoul, Korea.
Present address: 3921 Omeara St., Houston, TX 77025.
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