This Article Full Text Full Text (PDF) Other Versions of this Article: JB.01409-07v1 190/8/2933    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Doughty, D. M. Articles by Bottomley, P. J. Search for Related Content PubMed PubMed Citation Articles by Doughty, D. M. Articles by Bottomley, P. J.

 Previous Article  |  Next Article 

Journal of Bacteriology, April 2008, p. 2933-2938, Vol. 190, No. 8
0021-9193/08/$08.00+0     doi:10.1128/JB.01409-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Evidence for Involvement of Copper Ions and Redox State in Regulation of Butane Monooxygenase in Pseudomonas butanovora

Department of Microbiology,¹ Department of Botany and Plant Pathology,² Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon 97331-3804³

Received 30 August 2007/ Accepted 5 February 2008

Pseudomonas butanovora possesses an alcohol-inducible alkane monooxygenase, butane monooxygenase (BMO), that initiates growth on C₂-C₉ alkanes. A lacZ transcriptional reporter strain, P. butanovora bmoX::lacZ, in which the BMO promoter controls the expression of β-galactosidase activity, was used to show that 1-butanol induced the BMO promoter in the presence or absence of O₂ when lactate-grown, BMO-repressed cells were washed free of lactate and incubated in NH₄Cl-KNa phosphate buffer. In contrast, when lactate-grown cells of the reporter strain were incubated in phosphate buffer containing the mineral salts of standard growth medium, 1-butanol-dependent induction was significantly repressed at low O₂ (1 to 2% [vol/vol]) and totally repressed under anoxic conditions. The repressive effect of the mineral salts was traced to its copper content. In cells exposed to 1% (vol/vol) O₂, CuSO₄ (0.5 µM) repressed 1-butanol-dependent induction of β-galactosidase activity. Under oxic conditions (20% O₂ [vol/vol]), significantly higher concentrations of CuSO₄ (2 µM) were required for almost complete repression of induction in lactate-grown cells. A combination of the Cu²⁺ reducing agent Na ascorbate (100 µM) and CuSO₄ (0.5 µM) repressed the induction of β-galactosidase activity under oxic conditions to the same extent that 0.5 µM CuSO₄ alone repressed it under anoxic conditions. Under oxic conditions, 2 µM CuSO₄ repressed induction of the BMO promoter less effectively in butyrate-grown cells of the bmoX::lacZ strain and of an R8-bmoX::lacZ mutant reporter strain with a putative BMO regulator, BmoR, inactivated. Under anoxic conditions, CuSO₄ repression remained highly effective, regardless of the growth substrate, in both BmoR-positive and -negative reporter strains.

Published ahead of print on 15 February 2008.