CONSTRUCTION OF RECOMBINANT K88 DNA WITH P-TAC PROMOTER

The gene encoding K88ab was localized on the 11.6 kb HindIII-HindIII f ragment of 74 kb plasmid DNA of E. coli 7301. The smallest recombinant DNA producing the K88ab antigen was obtained by excision of the 5.15 kb EcoRI-EcoRI fragment from recombinant DNA composed of the 11.6 kb K 88ab fragment in the pBR322 vector. The size of the smallest fragment was 6.5 kb. Expression of the K88ab antigen was controlled by the p1 p romoter of the pBR322 vector. Substitution of promoter P-tac for promo ter p1 made it possible to achieve expression of the K88ab antigen by E. coli MT. Substitution of promoter P-L for promoter P1 failed to ach ieve expression of the K88ab antigen in the recipient strains used.