title: The locus coding for the 3-nitrobenzoate dioxygenase of Comamonas sp. strain JS46 is flanked by IS1071 elements and is subject to deletion and inversion events.
abstract: In Comamonas sp. strain JS46, 3-nitrobenzoate (3Nba) is initially oxidized at the 3,4 position by a dioxygenase, which results in release of nitrite and production of protocatechuate. The locus coding for the 3Nba dioxygenase (designated mnb, for m-nitrobenzoate) was mobilized from strain JS46 using a plasmid capture method, cloned, and sequenced. The 3Nba dioxygenase (MnbA) is a member of the phthalate family of aromatic oxygenases. An open reading frame designated mnbB that codes for an NAD(P)H-dependent class IA aromatic oxidoreductase is downstream of mnbA. MnbB is tentatively identified as the oxidoreductase that transfers reducing equivalents to MnbA in strain JS46. The mnb locus is flanked by IS1071 elements. The upstream element is interrupted by a novel insertion sequence designated ISCsp1, and the transposase genes of the flanking insertion elements are transcribed in the direction opposite the direction of mnbA transcription. Spontaneous deletion of mnb occurs because of homologous recombination between the directly repeated flanking IS1071 elements. In addition, in approximately 0.007 to 0.2% of any population of JS46 cells growing on 3Nba, alternative orientations of mnb relative to the flanking IS1071 elements are detected. These alternative forms are the result of inversions of mnb and the flanking IS1071 elements. Inversions appear to occur because of homologous recombination between the inverted repeats that flank the IS1071 elements.
authors.affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6. miguel_providenti@carleton.ca
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Providenti
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Shaye
authors.forename: Krista D
authors.initials: KD
authors.lastname: Lynes
authors.forename: Neil T
authors.initials: NT
authors.lastname: McKenna
authors.forename: Jason M
authors.initials: JM
authors.lastname: O'brien
authors.forename: Sarah
authors.initials: S
authors.lastname: Rosolen
authors.forename: R Campbell
authors.initials: RC
authors.lastname: Wyndham
authors.forename: Iain B
authors.initials: IB
authors.lastname: Lambert
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D020585:Comamonas / Q000201:enzymology* / Q000235:genetics; D004251:DNA Transposable Elements; D049308:Dioxygenases / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D008969:Molecular Sequence Data; D009579:Nitrobenzoates / Q000378:metabolism*; D011995:Recombination, Genetic
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D009579:Nitrobenzoates; D049308:Dioxygenases; C040770:3-nitrobenzoic acid