title: Role of the C-terminal lysine residues of streptococcal surface enolase in Glu- and Lys-plasminogen-binding activities of group A streptococci.
abstract: Streptococcal surface enolase (SEN) is a major plasminogen-binding protein of group A streptococci. Our earlier biochemical studies have suggested that the region responsible for this property is likely located at the C-terminal end of the SEN molecule. In the present study, the gene encoding SEN was cloned from group A streptococci M6 isolate D471. A series of mutations in the sen gene corresponding to the C-terminal region (428KSFYNLKK435) of the SEN molecule were created by either deleting one or more terminal lysine residues or replacing them with leucine. All purified recombinant SEN proteins with altered C-terminal ends were found to be enzymatically active and were analyzed for their Glu- and Lys-plasminogen-binding activities. Wild-type SEN bound to Lys-plasminogen with almost three times more affinity than to Glu-plasminogen. However, the recombinant mutant SEN proteins with a deletion of Lys434-435 or with K435L and K434-435L replacements showed a significant decrease in Glu- and Lys-plasminogen-binding activities. Accordingly, a streptococcal mutant expressing SEN-K434-435L showed a significant decrease in Glu- and Lys-plasminogen-binding activities. Biochemical and functional analyses of the isogenic mutant strain revealed a significant decrease in its abilities to cleave a chromogenic tripeptide substrate, acquire plasminogen from human plasma, and penetrate the extracellular matrix. Together, these data indicate that the last two C-terminal lysine residues of surface-exposed SEN contribute significantly to the plasminogen-binding activity of intact group A streptococci and hence to their ability to exploit host properties to their own advantage in tissue invasion.
authors.affiliation: Laboratory of Bacterial Pathogenesis, Public Health Research Institute, International Center for Public Health, Newark, New Jersey 07103-3535, USA.
authors.forename: Anne
authors.initials: A
authors.lastname: Derbise
authors.forename: Youngmia P
authors.initials: YP
authors.lastname: Song
authors.forename: Sonia
authors.initials: S
authors.lastname: Parikh
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Fischetti
authors.forename: Vijay
authors.initials: V
authors.lastname: Pancholi
mesh_terms: D001426:Bacterial Proteins; D006801:Humans; D008239:Lysine / Q000737:chemistry*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010446:Peptide Fragments / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010949:Plasma / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D011485:Protein Binding; D013297:Streptococcus pyogenes / Q000201:enzymology* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments; C018998:lysyl-plasminogen; D010958:Plasminogen; C112984:streptococcal surface enolase; D010751:Phosphopyruvate Hydratase; D008239:Lysine