title: Genomic and functional analysis of the IncP-9 naphthalene-catabolic plasmid NAH7 and its transposon Tn4655 suggests catabolic gene spread by a tyrosine recombinase.
abstract: The naphthalene-catabolic (nah) genes on the incompatibility group P-9 (IncP-9) self-transmissible plasmid NAH7 from Pseudomonas putida G7 are some of the most extensively characterized genetic determinants for bacterial aerobic catabolism of aromatic hydrocarbons. In contrast to the detailed studies of its catabolic cascade and enzymatic functions, the biological characteristics of plasmid NAH7 have remained unclear. Our sequence determination in this study together with the previously deposited sequences revealed the entire structure of NAH7 (82,232 bp). Comparison of NAH7 with two other completely sequenced IncP-9 catabolic plasmids, pDTG1 and pWW0, revealed that the three plasmids share very high nucleotide similarities in a 39-kb region encoding the basic plasmid functions (the IncP-9 backbone). The backbone of NAH7 is phylogenetically more related to that of pDTG1 than that of pWW0. These three plasmids carry their catabolic gene clusters at different positions on the IncP-9 backbone. All of the NAH7-specified nah genes are located on a class II transposon, Tn4655. Our analysis of the Tn4655-encoded site-specific recombination system revealed that (i) a novel tyrosine recombinase, TnpI, catalyzed both the intra- and intermolecular recombination between two copies of the attI site, (ii) the functional attI site was located within a 119-bp segment, and (iii) the site-specific strand exchange occurred within a 30-bp segment in the 41-bp CORE site. Our results and the sequence data of other naphthalene-catabolic plasmids, pDTG1 and pND6-1, suggest a potential role of the TnpI-attI recombination system in the establishment of these catabolic plasmids.
authors.affiliation: Department of Environmental Simulation, Institute for Environmental Sciences, Rokkasho, Aomori 039-3212, Japan. sota@uidaho.edu
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sota
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Yano
authors.forename: Akira
authors.initials: A
authors.lastname: Ono
authors.forename: Ryo
authors.initials: R
authors.lastname: Miyazaki
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ishii
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Genka
authors.forename: Eva M
authors.initials: EM
authors.lastname: Top
authors.forename: Masataka
authors.initials: M
authors.lastname: Tsuda
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005784:Gene Amplification; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009281:Naphthalenes / Q000378:metabolism*; D010957:Plasmids; D016133:Polymerase Chain Reaction; D045522:Recombinases / Q000235:genetics / Q000378:metabolism*; D015183:Restriction Mapping
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; D009281:Naphthalenes; D045522:Recombinases; C031721:naphthalene