title: Functional redundancy in phenol and toluene degradation in Pseudomonas stutzeri strains isolated from the Baltic Sea.
abstract: In the present study we describe functional redundancy of bacterial multicomponent monooxygenases (toluene monooxygenase (TMO) and toluene/xylene monooxygenase (XylAM) of TOL pathway) and cooperative genetic regulation at the expression of the respective catabolic operons by touR and xylR encoded regulatory circuits in five phenol- and toluene-degrading Pseudomonas stutzeri strains. In these strains both toluene degradation pathways (TMO and Xyl) are active and induced by toluene and phenol. The whole genome sequence of the representative strain 2A20 revealed the presence of complete TMO- and Xyl-upper pathway operons together with two sets of lower catechol meta pathway operons, as well as phenol-degrading operon in a single 292,430bp contig. The much lower GC content and analysis of the predicted ORFs refer to the plasmid origin of the approximately 130kb region of this contig, containing the xyl, phe and tou genes. The deduced amino acid sequences of the TMO, XylA and the large subunit of phenol monooxygenase (LmPH) show 98-100% identity with the respective gene products of the strain Pseudomonas sp. OX1. In both strains 2A20 and OX1 the meta-cleavage pathways for catechol degradation are coded by two redundant operons (phe and xyl). We show that in the strain 2A20 TouR and XylR are activated by different effector molecules, phenol and toluene, respectively, and they both control transcription of the xyl upper, tou (TMO) and phe catabolic operons. Although the growth parameters of redundant strains did not show advantage at toluene biodegradation, the functional redundancy could provide better flexibility to the bacteria in environmental conditions.
authors.affiliation: Institute of Molecular and Cell Biology, Department of Genetics, University of Tartu, 23 Riia Street, Tartu 51010, Estonia.
authors.forename: Eeva
authors.initials: E
authors.lastname: Heinaru
authors.affiliation: Institute of Molecular and Cell Biology, Department of Genetics, University of Tartu, 23 Riia Street, Tartu 51010, Estonia. Electronic address: eve.naanuri@ut.ee.
authors.forename: Eve
authors.initials: E
authors.lastname: Naanuri
authors.affiliation: Institute of Molecular and Cell Biology, Department of Genetics, University of Tartu, 23 Riia Street, Tartu 51010, Estonia.
authors.forename: Maarja
authors.initials: M
authors.lastname: Grünbach
authors.affiliation: Institute of Molecular and Cell Biology, Department of Genetics, University of Tartu, 23 Riia Street, Tartu 51010, Estonia.
authors.forename: Merike
authors.initials: M
authors.lastname: Jõesaar
authors.affiliation: Institute of Molecular and Cell Biology, Department of Genetics, University of Tartu, 23 Riia Street, Tartu 51010, Estonia.
authors.forename: Ain
authors.initials: A
authors.lastname: Heinaru
mesh_terms: D001267:Atlantic Ocean; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001454:Baltic States; D001482:Base Composition; D001673:Biodegradation, Environmental; D002396:Catechols / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D016366:Open Reading Frames; D009876:Operon; D010105:Oxygenases / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D044223:Pseudomonas stutzeri / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D014050:Toluene / Q000378:metabolism; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014992:Xylenes / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002396:Catechols; D014874:Water Pollutants, Chemical; D014992:Xylenes; D014050:Toluene; D010105:Oxygenases; C087733:toluene-3-monooxygenase; C067624:xylene monooxygenase
keywords: Functional redundancy; Phenol; Pseudomonas; Regulatory genes; Toluene degradation