Analysis of genes coding for the major and minor fimbrial subunits of the Prs-like fimbriae F165(1) of porcine septicemic Escherichia coli strain 4787.

Septicemic Escherichia coli 4787 of porcine origin produces a Prs-like fimbrial antigen, F165(1) which agglutinates sheep erythrocytes in a similar manner to Prs fimbriae, but unlike the latter, also agglutinates pig erythrocytes. In a previous study, we reported the cloning of the f165(1) operon and showed that it encodes a Prs-like adhesin. Here, we report the sequence of the f165(1)A, and f165(1)EFG genes. f165(1)A encodes a protein of 161 amino acids preceded by a signal peptide of 21 amino acids. A size of 19.3 kDa was calculated for the processed F165(1)A protein. The E, F, and G open reading frames potentially give rise to mature proteins of 149, 148 and 313 amino acids respectively. The F165(1)A protein showed significant similarity with the major subunit protein of P-fimbriae of F11 serotype, differing only in four positions. F165(1)E and F165(1)G were found to be closely related to the PrsE and PrsG proteins of Prs-fimbriae variants, whereas F165(1)F was found to be almost completely identical to the F protein of various P and Prs fimbriae. Our results indicated that the f165(1) is a mosaic operon consisting of sequences related to both the pap operon and the prs operon.