Studies on the expression and organization of the K88ac adherence antigen.

The genetic determinant for the K88ac adhesion antigen has been cloned on a 6.5 kilobasepair DNA fragment into the multiple copy plasmid pBR322. The resulting hybrid plasmid named pMK005 was used to study the organization and expression of polypeptides involved in K88ac antigen assembly. Five cistrons named adh A, B, C, D and E were mapped on the cloned DNA and maximal expression of K88ac antigen was found to be dependent on a pBR322 encoded promoter. Four polypeptides of molecular weights 70,000 daltons, 25,000 daltons, 17,000 daltons, and 23,500 daltons (K88ac fimbrial subunit) were identified as the products of the adh A, B, C and D cistrons respectively. The subcellular location of each of these polypeptides was determined by fractioning minicells. pMK005 encodes sufficient information to promote adhesion of a wild-type E. coli strain 09:K13:H19 to the porcine small intestine in vivo.