This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Cafaro, V.
Right arrow Articles by Di Donato, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Cafaro, V.
Right arrow Articles by Di Donato, A.
Agricola
Right arrow Articles by Cafaro, V.
Right arrow Articles by Di Donato, A.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, August 2005, p. 4736-4743, Vol. 71, No. 8
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.8.4736-4743.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Regiospecificity of Two Multicomponent Monooxygenases from Pseudomonas stutzeri OX1: Molecular Basis for Catabolic Adaptation of This Microorganism to Methylated Aromatic Compounds

Valeria Cafaro,{dagger} Eugenio Notomista,{dagger} Paola Capasso, and Alberto Di Donato*

Dipartimento di Biologia Strutturale e Funzionale, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia, 80126 Napoli, and CEINGE-Biotecnologie Avanzate S.c.ar.l., Napoli, Italy

Received 7 October 2004/ Accepted 25 February 2005

The pathways for degradation of aromatic hydrocarbons are constantly modified by a variety of genetic mechanisms. Genetic studies carried out with Pseudomonas stutzeri OX1 suggested that the tou operon coding for toluene o-xylene monooxygenase (ToMO) was recently recruited into a preexisting pathway that already possessed the ph operon coding for phenol hydroxylase (PH). This apparently resulted in a redundancy of enzymatic activities, because both enzymes are able to hydroxylate (methyl)benzenes to (methyl)catechols via the intermediate production of (methyl)phenols. We investigated the kinetics and regioselectivity of toluene and o-xylene oxidation using Escherichia coli cells expressing ToMO and PH complexes. Our data indicate that in the recombinant system the enzymes act sequentially and that their catalytic efficiency and regioselectivity optimize the degradation of toluene and o-xylene, both of which are growth substrates. The main product of toluene oxidation by ToMO is p-cresol, the best substrate for PH, which catalyzes its transformation to 4-methylcatechol. The sequential action of the two enzymes on o-xylene leads, via the intermediate 3,4-dimethylphenol, to the exclusive production of 3,4-dimethylcatechol, the only dimethylcatechol isomer that can serve as a carbon and energy source after further metabolic processing. Moreover, our data strongly support a metabolic explanation for the acquisition of the ToMO operon by P. stutzeri OX1. It is possible that using the two enzymes in a concerted fashion confers on the strain a selective advantage based on the ability of the microorganism to optimize the efficiency of the use of nonhydroxylated aromatic hydrocarbons, such as benzene, toluene, and o-xylene.

* Corresponding author. Mailing address: Dipartimento di Biologia strutturale e funzionale, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia, 80126 Napoli, Italy. Phone: 39-081-674426. Fax: 39-081-674414. E-mail: didonato{at}unina.it.

{dagger} V.C. and E.N. contributed equally to this paper.

Applied and Environmental Microbiology, August 2005, p. 4736-4743, Vol. 71, No. 8
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.8.4736-4743.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Notomista, E., Cafaro, V., Bozza, G., Di Donato, A. (2009). Molecular Determinants of the Regioselectivity of Toluene/o-Xylene Monooxygenase from Pseudomonas sp. Strain OX1. Appl. Environ. Microbiol. 75: 823-836 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»