title: Characterization of the traD operon of naphthalene-catabolic plasmid NAH7: a host-range modifier in conjugative transfer.
abstract: Pseudomonas putida G7 carries a naphthalene-catabolic and self-transmissible plasmid, NAH7, which belongs to the IncP-9 incompatibility group. Adjacent to the putative origin of conjugative transfer (oriT) of NAH7 are three genes, traD, traE, and traF, whose functions and roles in conjugation were previously unclear. These three genes were transcribed monocistronically and thus were designated the traD operon. Mutation of the three genes in the traD operon resulted in 10- to 10(5)-fold decreases in the transfer frequencies of the plasmids from Pseudomonas to Pseudomonas and Escherichia coli and from E. coli to E. coli. On the other hand, the traD operon was essential for the transfer of NAH7 from E. coli to Pseudomonas strains. These results indicated that the traD operon is a host-range modifier in the conjugative transfer of NAH7. The TraD, TraE, and TraF proteins were localized in the cytoplasm, periplasm, and membrane, respectively, in strain G7 cells. Our use of a bacterial two-hybrid assay system showed that TraE interacted in vivo with other essential components for conjugative transfer, including TraB (coupling protein), TraC (relaxase), and MpfH (a channel subunit in the mating pair formation system).
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Miyazaki
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohtsubo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagata
authors.forename: Masataka
authors.initials: M
authors.lastname: Tsuda
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003227:Conjugation, Genetic; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D009154:Mutation; D009281:Naphthalenes / Q000378:metabolism*; D009876:Operon / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*; D011485:Protein Binding; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D009281:Naphthalenes; C064957:traD protein, E coli; C031721:naphthalene