α-enolase, a plasmin(ogen) binding and cell wall associating protein from a fish pathogenic Streptococcus iniae strain

The plasmin(ogen) binding property of pathogenic bacteria is suggested to be one of the characteristics that may contribute to tissue invasion. Recently, the presence of a surface-localized α-enolase that binds both plasmin and plasminogen has been reported from Streptococcus pyogenes and from S. pneumoniae. To investigate whether α-enolase of S. iniae has similar characteristics to that of the above streptococci, in the present study, we have produced α-enolase as a recombinant protein from a fish pathogenic S. iniae strain, and demonstrated for the first time its plasmin(ogen)-binding ability and cell wall-association using immunoblot method. These results suggest that α-enolase of S. iniae may be responsible in part for the ability of S. iniae to cross tissue barriers through plasminogen activation.