Complete nucleotide sequence of plasmid pND6-2 from Pseudomonas putida ND6 and characterization of conjugative genes

Pseudomonas putida ND6 was shown to be capable of growth using naphthalene as sole carbon and energy sources. One plasmid from this strain, pND6-1, which was associated with the metabolism of naphthalene, was characterized; and the complete nucleotide sequence (101,858bp) and annotation of the plasmid were reported previously. In this paper, another plasmid (117,003bp) from P. putida ND6, pND6-2, was sequenced and 136 putative coding sequences (CDSs) were annotated. Among them, 9 CDSs were predicted to be involved in replication and partition of the plasmid, 32 CDSs encoded proteins associated with plasmid conjugative transfer, 2 CDSs encoded transcriptional regulators, 9 CDSs were necessary for DNA-associated function (including metabolism, recombination and repair), and 5 CDSs encoded proteins associated with other functions. The filter matting experiment indicated that pND6-2 is a helper plasmid, which could assist the naphthalene catabolic plasmid pND6-1 without any conjugative genes being transferred from P. putida ND6 to Escherichia coli AD256. ► The complete 117,003-bp sequence of the plasmid pND6-2 was determined. ► Plasmid pND6-2 carried 136 potential CDSs. ► Thirty-two CDSs encoded proteins associated with plasmid conjugative transfer. ► Plasmid pND6-2 is a helper plasmid that could mobilize plasmid pND6-1.