GENETIC ORGANIZATION OF THE TRANSFER REGION OF F-LIKE PLASMID-PAP18-1

Conjugation transfer of F plasmid and certain F-like plasmids is connected with the presence of a tra region in their genome, consisting of tra genes, under the control of which plasmid-specific pili and other phenotypic manifestations of the transfer system of bacterial cells containing these plasmids are formed [2, 6, 7, 10, 11]. However, the organization of genetic control of transfer of other F-like plasmids, notably plasmids found in bacteria of natural populations, has not yet been studied. The aim of this investigation was to identify genes of the tra region and to determine its possible location in the genome of a derepressed (drd) mutant of F-like plasmid pAP18-1 (Tc, ColV), found previously in cells of a strain of Escherichia coli isolated from a sick calf [3]. The problem was solved by identifying Tra(-)-mutants and molecular cloning of plasmid pAP18-ldrd.