PMID: 15232158Jul 3, 2004Paper

Characterization of plasmin(ogen) binding to Streptococcus pneumoniae

The Indian Journal of Medical Research
Simone BergmannSven Hammerschmidt

Abstract

The proteolytic activity of plasmin promotes migration of pathogenic bacteria through the human extracellular matrix. The human pathogen Streptococcus pneumoniae binds both human plasminogen and plasmin via the surface displayed alpha-enolase designated Eno. Electron microscopic studies verified the surface exposition of the glycolytic enzyme alpha-enolase and moreover, its ability to reassociate to the cell surface. Carboxyterminal lysine residues of recently described eukaryotic and prokaryotic plasminogen-binding proteins such as SEN of S. pyogenes are involved in interaction with lysine binding sites of kringle domains of plasminogen. In this study, the role of carboxy terminal lysyl residue of eno in plasminogen binding is further analysed. Site-directed mutagenesis of eno gene was done using DNA primers with Hind III-restriction enzyme sites for cloning. Purified Eno fusion proteins were separated by SDS-PAGE and human plasminogen binding assay was performed. Radioiodinated ligand binding was done by competitive inhibition assay. Binding assays performed under reduced conditions indicated also a role of the C-terminal lysyl residues of Eno for plasmin(ogen) binding. Binding of pneumococci to radioiodinated plasminogen was...Continue Reading

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