COLICIN-24, A NEW PLASMID-BORNE COLICIN FROM A UROPATHOGENIC STRAIN OF ESCHERICHIA-COLI

A new colicin, as defined by cross-immunity tests against the colicin reference set, has been identified from a uropathogenic Escherichia co li isolate (strain 2424), collected from a pyelonephritis patient at C hristchurch Hospital. This toxin, colicin 24, is active against E. col i and Salmonella typhimurium, and the genes involved in colicin 24 pro duction, transport, and immunity were found to reside on a 43.54-kb co njugative plasmid, p24-2. Mutagenesis using mini-Tn10 has identified t wo consecutive EcoRI fragments on p24-2 that contain all the colicin 2 4 determinants. A 25.14-kb BamHI-HindIII fragment containing this regi on was cloned from a mutant with a normal colicin phenotype into pBR32 2 to form the recombinant plasmid pGOB34. Subcloning of pGOB34 has res ulted in an 8.7-kb fragment containing all the colicin 24 determinants being cloned into pUC 18 to form pGOB342. (C) 1994 Academic Press, In c.