Oxidative stress response in an anaerobe Bacteroides fragilis: a role for catalase in protection against hydrogen peroxide.

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

James P. Coleman (Creator)

Edson R. Rocha (Creator)

Tina Selby (Creator)

C. Jeffrey Smith (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Survival of Bacteroides fragilis in the presence of oxygen was dependent on the ability of bacteria to synthesize ew proteins as determined by the inhibition of protein synthesis after oxygen exposure. The B. fragilis protein rofile was significantly altered after either a shift from anaerobic to aerobic conditions with or without araquat or the addition of exogenous hydrogen peroxide. As determined by autoradiography after twodimensional el electrophoresis approximately 28 newly synthesized proteins were detected in response to xidative conditions. These proteins were found to have a broad range of pI values (from 5.1 to 7.2) and olecular weights (from 12 000 to 79 000). The hydrogen peroxide- and paraquat-inducible responses were imilar but not identical to that induced by oxygen as seen by two-dimensional gel protein profile. Eleven of the xidative response proteins were closely related with pI values and molecular weights from 5.1 to 5.8 and from 17,000 to 23,000 respectively. As a first step to understanding the resistance to oxygen a catalase-deficient utant was constructed by allelic gene exchange. The katB mutant was found to be more sensitive to the lethal ffects of hydrogen peroxide than was the parent strain when the ferrous iron chelator bipyridyl was added to ulture media. This suggests that the presence of ferrous iron in anaerobic culture media exacerbates the oxicity of hydrogen peroxide and that the presence of a functional catalase is important for survival in the resence of hydrogen peroxide. Further the treatment of cultures with a sublethal concentration of hydrogen eroxide was necessary to induce resistance to higher concentrations of hydrogen peroxide in the parent strain uggesting that this was an inducible response. This was confirmed when the bacterial culture treated with hloramphenicol before the cells were exposed to a sublethal concentration of peroxide completely lost iability. In contrast cell viability was greatly preserved when protein synthesis inhibition occurred after eroxide induction. Complementation of catalase activity in the mutant restored the ability of the mutant train to survive in the presence of hydrogen peroxide showing that the catalase (KatB) may play a role in xidative stress resistance in aerotolerant anaerobic bacteria. Originally published Journal of Bacteriology Vol. 178 No. 23 Dec. 1996

Additional Information

Publication

Other

Journal of Bacteriology. 178:23(December 1996) p. 6895-6903.

Language: English

Date: 2011

Keywords

Oxidative stress, catalase, hydrogen peroxide resistance

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