Regulator and enzyme specificities of the TOL plasmid-encoded upper pathway for degradation of aromatic hydrocarbons and expansion of the substrate range of the pathway
- 1 December 1989
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 171 (12), 6782-6790
- https://doi.org/10.1128/jb.171.12.6782-6790.1989
Abstract
The TOL plasmid upper pathway operon encodes enzymes involved in the catabolism of aromatic hydrocarbons such as toluene and xylenes. The regulator of the gene pathway, the XylR protein, exhibits a very broad effector specificity, being able to recognize as effectors not only pathway substrates but also a wide variety of mono- and disubstituted methyl-, ethyl-, and chlorotoluenes, benzyl alcohols, and p-chlorobenzaldehyde. Benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase, two upper pathway enzymes, exhibit very broad substrate specificities and transform unsubstituted substrates and m- and p-methyl-, m- and p-ethyl-, and m- and p-chloro-substituted benzyl alcohols and benzaldehydes, respectively, at a high rate. In contrast, toluene oxidase only oxidizes toluene, m- and p-xylene, m-ethyltoluene, and 1,2,4-trimethylbenzene [corrected], also at a high rate. A biological test showed that toluene oxidase attacks m- and p-chlorotoluene, albeit at a low rate. No evidence for the transformation of p-ethyltoluene by toluene oxidase has been found. Hence, toluene oxidase acts as the bottleneck step for the catabolism of p-ethyl- and m- and p-chlorotoluene through the TOL upper pathway. A mutant toluene oxidase able to transform p-ethyltoluene was isolated, and a mutant strain capable of fully degrading p-ethyltoluene was constructed with a modified TOL plasmid meta-cleavage pathway able to mineralize p-ethylbenzoate. By transfer of a TOL plasmid into Pseudomonas sp. strain B13, a clone able to slowly degrade m-chlorotoluene was also obtained.Keywords
This publication has 19 references indexed in Scilit:
- Catabolism of Aromatic Hydrocarbons by PseudomonasPublished by Elsevier BV ,1989
- Microbial metabolism of mandelate: a microcosm of diversityFEMS Microbiology Letters, 1988
- Regulatory circuits controlling transcription of TOL plasmid operon encoding meta‐cleavage pathway for degradation of alkylbenzoates by PseudomonasMolecular Microbiology, 1987
- Redesigning Metabolic Routes: Manipulation of TOL Plasmid Pathway for Catabolism of AlkylbenzoatesScience, 1987
- The pUC plasmids, an M13mp7-derived system for insertion mutagenesis and sequencing with synthetic universal primersGene, 1982
- Construction of haloaromatics utilising bacteriaNature, 1979
- Chemical structure and biodegradability of halogenated aromatic compounds substituent effects on 1,2-dioxygenation of benzoic acidBiochimica et Biophysica Acta (BBA) - General Subjects, 1978
- A Rapid and Sensitive Method for the Quantitation of Microgram Quantities of Protein Utilizing the Principle of Protein-Dye BindingAnalytical Biochemistry, 1976
- A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye bindingAnalytical Biochemistry, 1976
- Isolation and characterization of a 3-chlorobenzoate degrading pseudomonadArchiv für Mikrobiologie, 1974