CLONING AND EXPRESSION OF 2 PASTEURELLA-MULTOCIDA GENES IN ESCHERICHIA-COLI

A library of cloned Pasteurella multocida (toxigenic strain 9222, sero type D2) genomic sequences was constructed in Escherichia coli by inco rporating TaqI digestion fragments into the plasmid vector pUC19. Immu nological screening with antibodies directed against porin H, the majo r protein of the P multocida outer membrane, allowed the identificatio n of a recombinant plasmid containing a 2.9-kbp DNA insert. This plasm id encoded the synthesis of two polypeptides, p25 (25 kDa) and p28 (28 kDa) which were detected in the different compartments of the E coli transformant. The peptide p25 was more abundant in the periplasm where as p28 was mainly found in the cell envelope and in the cytosol. Immun ological analysis indicates that p25, in contrast to p28, is antigenic ally related to porin H of P multocida. The expression in E coli of th e gene encoding p28 was enhanced by induction of the lac promoter.