IDENTIFICATION AND EXPRESSION OF PLASMID GENES INVOLVED IN SYNTHESIS OF MICROCIN C51

A structural gene of heptapeptide, which is a component of the microci n C51 molecule, was identified by hybridization of plasmid DNA fragmen ts and a mixture of synthesized oligonucleotides with the sequence cor responding to that of amino acids in the peptide. Sequence analysis of the structural gene of microcin peptide and its promoter region was p erformed. The data obtained indicate that the peptide of microcin C51 is synthesized on ribosomes. Four polypeptides of 67, 39, 16, and 14 k Da were identified using the system of minicells, These polypeptides a re specified by a DNA fragment responsible for microcin synthesis and immunity in a producer cell, Apparently, three of these polypeptides w ith molecular masses of 67, 39, and 16 kDa are responsible for microci n production and immunity. The 67 kDa polypeptide is involved in the e xpression of immunity to microcin and, probably, in microcin productio n.