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J. Bacteriol., Nov 1995, 6536-6544, Vol 177, No. 22
SM Brown, ML Howell, ML Vasil, AJ Anderson and DJ Hassett
Pseudomonas aeruginosa is an obligate aerobe that is virtually ubiquitous
in the environment. During aerobic respiration, the metabolism of dioxygen
can lead to the production of reactive oxygen intermediates, one of which
includes hydrogen peroxide. To counteract the potentially toxic effects of
this compound, P. aeruginosa possesses two heme-containing catalases which
detoxify hydrogen peroxide. In this study, we have cloned katB, encoding
one catalase gene of P. aeruginosa. The gene was cloned on a 5.4-kb EcoRI
fragment and is composed of 1,539 bp, encoding 513 amino acids. The amino
acid sequence of the P. aeruginosa katB was approximately 65% identical to
that of a catalase from a related species, Pseudomonas syringae. The katB
gene was mapped to the 71- to 75-min region of the P. aeruginosa
chromosome, the identical region which harbors both sodA and sodB genes
encoding both manganese and iron superoxide dismutases. When cloned into a
catalase-deficient mutant of Escherichia coli (UM255), the recombinant P.
aeruginosa KatB was expressed (229 U/mg) and afforded this strain
resistance to hydrogen peroxide nearly equivalent to that of the wild- type
E. coli strain (HB101). The KatB protein was purified to homogeneity and
determined to be a tetramer of approximately 228 kDa, which was in good
agreement with the predicted protein size derived from the translated katB
gene. Interestingly, KatB was not produced during the normal P. aeruginosa
growth cycle, and catalase activity was greater in nonmucoid than in
mucoid, alginate-producing organisms. When exposed to hydrogen peroxide
and, to a greater extent, paraquat, total catalase activity was elevated 7-
to 16-fold, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Cloning and characterization of the katB gene of Pseudomonas aeruginosa encoding a hydrogen peroxide-inducible catalase: purification of KatB, cellular localization, and demonstration that it is essential for optimal resistance to hydrogen peroxide
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Ohio 45267-0524, USA.
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