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Title: Heterologous growth phase- and temperature-dependent expression and H<inf>2</inf>O<inf>2</inf>toxicity protection of a superoxide-inducible monofunctional catalase gene from Xanthomonas oryzae pv. oryzae
Authors: Skorn Mongkolsuk
Suvit Loprasert
Paiboon Vattanaviboon
Chaninchon Chanvanichayachai
Sangpen Chamnongpol
Niwat Supsamran
Chulabhorn Research Institute
Mahidol University
Universiteit Gent
Keywords: Biochemistry, Genetics and Molecular Biology;Immunology and Microbiology
Issue Date: 1-Jan-1996
Citation: Journal of Bacteriology. Vol.178, No.12 (1996), 3578-3584
Abstract: Catalase is an important protective enzyme against H2O2toxicity. Here, we report the characterization of a Xanthomonas oryzae pv. oryzae catalase gene (katX). The gene was localized and its nucleotide sequence was determined. The gene codes for a 77-kDa polypeptide. The deduced katX amino acid sequence shares regions of high identity with other monofunctional catalases in a range of organisms from bacteria to eukaryotes. The transcriptional regulation of katX was atypical of bacterial monofunctional kat genes. Northern (RNA) analysis showed that katX transcription was highly induced by treatments with low concentrations of menadione, a superoxide generator, and methyl methanesulfonate, a mutagen. It was only weakly induced by H2O2. Unlike in other bacteria, a high level of catalase in Xanthomonas spp. provided protection from the growth-inhibitory and killing effects of H2O2but not from those of organic peroxides and superoxide generators. Unexpectedly, heterologous expression of katX in Escherichia coli was both growth phase and temperature dependent. Catalase activity in E. coli kat mutants harboring katX on an expression vector was detectable only when the cells entered the stationary phase of growth and at 28°C. The patterns of transcription regulation, heterologous expression, and physiological function of katX are different from previously studied bacterial kat genes.
ISSN: 00219193
Appears in Collections:Scopus 1991-2000

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