Molecular characterization of a DNA fragment carrying the basic replicon of pTUC100, the natural plasmid encoding the peptide antibiotic microcin J25 system

DELGADO, MONICA ALEJANDRA; SALOMON, RAUL A.; DELGADO, MONICA ALEJANDRA

PLASMID.

Elsevier

Año: 2005 vol. 53 p. 258 - 262

0147-619X

The Escherichia coli plasmid pTUC100 encodes production of, and immunity to, the peptide antibiotic microcin J25. In the present study, an approximately 8-kb fragment immediately adjacent to the previously sequenced microcin region was isolated and its DNA sequence was determined. The main features of the newly characterized region are: (i) a basic replicon which is almost identical to that of the RepFIIA plasmid R100; (ii) two ORFs with 96% identity to two ORFs of unknown function on pO157, a large plasmid  harbored by enterohemorragic E. coli, and a large ORF which does not show significant homology to any other reported nucleotide or protein sequence; and (iii) two intact insertion sequences, IS1294 and IS1. Sequence analysis, as well as that of the G + C content of both the 8-kb fragment and the previously sequenced microcin locus, lead us to propose that plasmid pTUC100 is a composite structure assembled from DNA elements from various sources.