Comparison of the fibronectin-binding protein FNE from Streptococcus equi subspecies equi with FNZ from S-equi subspecies zooepidemicus reveals a major and conserved difference

The gene fnz from Streptococcus equi subspecies zooepidemicus encodes a tel l surface protein that binds fibronectin (Fn), Fifty tested isolates of S, equi subspecies equi all contain DNA sequences with similarity to fnz, This work describes the cloning and sequencing of a gene, designated fne, with similarity to,fnz from two S, equi subspecies equi isolates. The DNA sequen ces were found to be identical in the two strains, and sequence comparison of the fne and fnz genes revealed only. minor differences, However, one bas e deletion was found in the middle of the fne gene and eight base pairs dow nstream of the altered reading frame there is a stop codon, tin Fn-binding protein aas purified from the growth medium of a subspecies Equi culture, D etermination of the NH2-terminal amino acid sequence and molecular mass, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revea led that the purified protein is the gene product of the 5'-terminal half o f fne, Fn-binding activity has earlier only been found in the COOH-terminal half of FNZ, By the use of a purified recombinant protein containing the N H2 half of FNZ, we provide here evidence that this half of the protein also harbors an Fn-binding domain.