This Article Full Text (PDF) Other Versions of this Article: JB.00950-06v1 189/1/207    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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Duque, E. Articles by Ramos, J.-L. Search for Related Content PubMed PubMed Citation Articles by Duque, E. Articles by Ramos, J.-L.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.00950-06
Copyright (c) 2006, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

The RpoT regulon of Pseudomonas putida DOT-T1E and its role in stress endurance against solvents

CSIC-Estación Experimental del Zaidín, Department of Environmental Protection, Profesor Albareda, 1, E-18008 Granada, Spain

^* To whom correspondence should be addressed. Email: jlramos{at}eez.csic.es.

	Abstract

Pseudomonas putida encodes 20 extracytoplasmic sigma factors (ECFs). In this study we show that one of these ECFs, known as ECF-Pp-12 (PP3006), plays a role in tolerance to toluene and other organic solvents. Based on this finding, we have called the gene that encodes this new ECF rpoT. The rpoT gene forms an operon with the preceding gene and with the gene located downstream. The translated gene product of the open reading frame PP3005 is an inner membrane protein, whereas the PP3007 protein is periplasmic. A nonpolar rpoT mutant was generated by homologous recombination, and survival of the mutant was tested under various stress conditions. The mutant strain was hypersensitive to toluene and other solvents, but just as tolerant as the wild type to stress imposed by heat, antibiotics, NaCl, paraquat, sodium dodecyl sulfate, H₂O₂ and benzoate. In the rpoT mutant background, expression of around 50 transcriptional units was affected: 31 cistrons were upregulated, and 23 cistrons were downregulated. This indicates that about 1% of all P. putida genes are under the direct or indirect influence of RpoT. The rpoT gene controls the expression of a number of membrane proteins, including components of the respiratory chains, porins, transporters and multidrug efflux pumps. Hypersensitivity of the P. putida RpoT-deficient mutant to organic solvents can be attributed to the fact that in the rpoT strain, expression of the toluene efflux pump ttgGHI genes is several fold lower than in the parental strain.

This article has been cited by other articles:

• del Castillo, T., Duque, E., Ramos, J. L. (2008). A Set of Activators and Repressors Control Peripheral Glucose Pathways in Pseudomonas putida To Yield a Common Central Intermediate. J. Bacteriol. 190: 2331-2339 [Abstract] [Full Text]  
• del Castillo, T., Ramos, J. L., Rodriguez-Herva, J. J., Fuhrer, T., Sauer, U., Duque, E. (2007). Convergent Peripheral Pathways Catalyze Initial Glucose Catabolism in Pseudomonas putida: Genomic and Flux Analysis. J. Bacteriol. 189: 5142-5152 [Abstract] [Full Text]