HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Vattanaviboon, P. Articles by Mongkolsuk, S. Search for Related Content PubMed PubMed Citation Articles by Vattanaviboon, P. Articles by Mongkolsuk, S. Agricola Articles by Vattanaviboon, P. Articles by Mongkolsuk, S.

Catalase has a novel protective role against electrophile killing of Xanthomonas

Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand¹
Department of Biotechnology, Faculty of Science, Mahidol University, Rama 6 Rd, Bangkok 10400, Thailand²

Author for correspondence: Skorn Mongkolsuk. Tel: +662 574 0622 ext.1402. Fax: +662 574 2027. e-mail: skorn{at}tubtim.cri.or.th

The ability of Xanthomonas campestris pv. phaseoli to protect itself against lethal concentrations of man-made (N-ethylmaleimide, NEM) and endogenously produced (methylglyoxal, MG) electrophiles was investigated. Pretreatment of X. c. pv. phaseoli with a low concentration of NEM induced protection against lethal concentrations of NEM and MG. MG pretreatment weakly induced protection against NEM but not against MG itself. NEM-induced protection against electrophile killing required new protein synthesis and was abolished by the addition of a protein synthesis inhibitor. By contrast, MG-induced protection against NEM killing was independent of de novo protein synthesis. X. c. pv. phaseoli harbouring an expression vector carrying a catalase gene was over 100-fold more resistant to MG and NEM killing. High expression levels of genes for other peroxide-protective enzymes, such as those for alkyl hydroperoxide reductase (ahpC and ahpF) and ohr, failed to protect against electrophile killing. Thus, catalase appears to have a novel protective role(s) against electrophile toxicity. This finding suggests that in X. c. pv. phaseoli NEM and MG toxicity might involve accumulation and/or increased production of H₂O₂. This idea was supported by the observation that addition of 10 mM sodium pyruvate, a compound that can react chemically with peroxide or hydroxyl radical scavengers (DMSO and glycerol), was found to protect Xanthomonas from electrophile killing. The protective role of catalase and the role of H₂O₂ in electrophile toxicity are novel observations and could be generally important in other bacteria. In addition, unlike other bacteria, Xanthomonas in stationary phase was more susceptible to electrophile killing compared to cells in exponential phase.

Keywords: methylglyoxal, N-ethylmaleimide, resistance, catalase

Abbreviations: MG, methylglyoxal; NEM, N-ethylmaleimide; SB, Silva–Buddenhagen

^a Present address: Department of Biotechnology, Faculty of Engineering, Osaka University, Osaka, Japan.

This article has been cited by other articles:

				N. Chauvatcharin, S. Atichartpongkul, S. Utamapongchai, W. Whangsuk, P. Vattanaviboon, and S. Mongkolsuk Genetic and physiological analysis of the major OxyR-regulated katA from Xanthomonas campestris pv. phaseoli Microbiology, February 1, 2005; 151(2): 597 - 605. [Abstract] [Full Text] [PDF]