Dataset Information

Identification of a new gene, tmoF, in the Pseudomonas mendocina KR1 gene cluster encoding toluene-4-monooxygenase.

ABSTRACT: Five genes, tmoABCDE, encoding toluene-4-monooxygenase (T4MO) were previously mapped to a 3.6-kb region of a 10.2-kb SacI DNA fragment isolated from Pseudomonas mendocina KR1 (K.-M. Yen, M. R. Karl, L. M. Blatt, M. J. Simon, R. B. Winter, P. R. Fausset, H. S. Lu, A. A. Harcourt, and K. K. Chen, J. Bacteriol. 173:5315-5327, 1991). In this report, we describe the identification and characterization of a DNA region in the SacI fragment whose expression enhances the T4MO activity determined by the tmoABCDE gene cluster. This region was mapped immediately downstream of the putative transcription termination sequence previously located at the end of the tmoABCDE gene cluster (Yen et al., J. Bacteriol., 1991) and was found to stimulate T4MO activity two- to threefold when expressed in Escherichia coli or Pseudomonas putida. Determination of the nucleotide sequence of this region revealed an open reading frame (ORF) of 978 bp. Expression of the ORF resulted in the synthesis of an approximately 37-kDa polypeptide whose N-terminal amino acid sequence completely matched that of the product predicted from the ORF. The ORF thus defines a gene, which has now been designated tmoF. The TmoF protein shares amino acid sequence homology with the reductases of several mono- and dioxygenase systems. In addition, the reductase component of the naphthalene dioxygenase system, encoded by the nahAa gene of plasmid NAH7 from P. putida G7, could largely replace the TmoF protein in stimulating T4MO activity, and TmoF could partially replace the NahAa protein in forming active naphthalene dioxygenase. The overall properties of tmoF suggest that it is a member of the T4mo gene cluster and encodes the NADH:ferredoxin oxidoreductase of the T4MO system.

SUBMITTER: Yen KM

PROVIDER: S-EPMC207419 | biostudies-other | 1992 Nov

REPOSITORIES: biostudies-other

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Identification of a new gene, tmoF, in the Pseudomonas mendocina KR1 gene cluster encoding toluene-4-monooxygenase.

Yen K M KM Karl M R MR

Journal of bacteriology 19921101 22

Five genes, tmoABCDE, encoding toluene-4-monooxygenase (T4MO) were previously mapped to a 3.6-kb region of a 10.2-kb SacI DNA fragment isolated from Pseudomonas mendocina KR1 (K.-M. Yen, M. R. Karl, L. M. Blatt, M. J. Simon, R. B. Winter, P. R. Fausset, H. S. Lu, A. A. Harcourt, and K. K. Chen, J. Bacteriol. 173:5315-5327, 1991). In this report, we describe the identification and characterization of a DNA region in the SacI fragment whose expression enhances the T4MO activity determined by the t ...[more]

PMID: 1429451

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Project description:It was previously shown by others that Pseudomonas sp. strain JS150 metabolizes benzene and alkyl- and chloro-substituted benzenes by using dioxygenase-initiated pathways coupled with multiple downstream metabolic pathways to accommodate catechol metabolism. By cloning genes encoding benzene-degradative enzymes, we found that strain JS150 also carries genes for a toluene/benzene-2-monooxygenase. The gene cluster encoding a 2-monooxygenase and its cognate regulator was cloned from a plasmid carried by strain JS150. Oxygen (18O2) incorporation experiments using Pseudomonas aeruginosa strains that carried the cloned genes confirmed that toluene hydroxylation was catalyzed through an authentic monooxygenase reaction to yield ortho-cresol. Regions encoding the toluene-2-monooxygenase and regulatory gene product were localized in two regions of the cloned fragment. The nucleotide sequence of the toluene/benzene-2-monooxygenase locus was determined. Analysis of this sequence revealed six open reading frames that were then designated tbmA, tbmB, tbmC, tbmD, tbmE, and tbmF. The deduced amino acid sequences for these genes showed the presence of motifs similar to well-conserved functional domains of multicomponent oxygenases. This analysis allowed the tentative identification of two terminal oxygenase subunits (TbmB and TbmD) and an electron transport protein (TbmF) for the monooxygenase enzyme. In addition to these gene products, all the tbm polypeptides shared significant homology with protein components from other bacterial multicomponent monooxygenases. Overall, the tbm gene products shared greater similarity with polypeptides from the phenol hydroxylases of Pseudomonas putida CF600, P35X, and BH than with those from the toluene monooxygenases of Pseudomonas mendocina KR1 and Burkholderia (Pseudomonas) pickettii PKO1. The relationship found between the phenol hydroxylases and a toluene-2-monooxygenase, characterized in this study for the first time at the nucleotide sequence level, suggested that DNA probes used for surveys of environmental populations should be carefully selected to reflect DNA sequences corresponding to the metabolic pathway of interest.

Dataset Information

Identification of a new gene, tmoF, in the Pseudomonas mendocina KR1 gene cluster encoding toluene-4-monooxygenase.

Publications

Identification of a new gene, tmoF, in the Pseudomonas mendocina KR1 gene cluster encoding toluene-4-monooxygenase.

Similar Datasets

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