title: Purification of native alpha-enolase from Streptococcus pneumoniae that binds plasminogen and is immunogenic.
abstract: Many pathogenic bacteria express plasminogen receptors on their surface, which may play a role in the dissemination of organisms by binding plasminogen that, when converted to plasmin, can digest extracellular matrix proteins. A 45-kDa protein was purified from Streptococcus pneumoniae and confirmed as an alpha-enolase by its ability to catalyse the dehydration of 2-phospho-D-glycerate to phosphoenolpyruvate and by N-terminal sequencing. The activity of alpha-enolase was found in the cytoplasm and in whole cells. Activity was also demonstrated in cell wall fractions, which confirmed that alpha-enolase is a cytoplasmic antigen also expressed on the surface of S. pneumoniae. The plasminogen-binding activity of alpha-enolase was examined by Western blot, which showed that purified alpha-enolase was able to bind human plasminogen. Immunoblots of the purified 45-kDa alpha-enolase with 22 sera from patients with pneumococcal disease showed binding in 15 cases, indicating that pneumococcal enolase is immunogenic.
authors.affiliation: Department of Medical Microbiology, Royal Free and University College Medical School, London NW3 2PF.
authors.forename: G C
authors.initials: GC
authors.lastname: Whiting
authors.affiliation: Department of Medical Microbiology, Royal Free and University College Medical School, London NW3 2PF.
authors.forename: J T
authors.initials: JT
authors.lastname: Evans
authors.affiliation: Department of Medical Microbiology, Royal Free and University College Medical School, London NW3 2PF.
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.affiliation: Department of Medical Microbiology, Royal Free and University College Medical School, London NW3 2PF.
authors.forename: S H
authors.initials: SH
authors.lastname: Gillespie
mesh_terms: D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial / Q000097:blood; D016470:Bacteremia / Q000276:immunology / Q000382:microbiology; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010751:Phosphopyruvate Hydratase / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism*; D011008:Pneumococcal Infections / Q000276:immunology / Q000382:microbiology; D011956:Receptors, Cell Surface / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D013296:Streptococcus pneumoniae / Q000201:enzymology* / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000907:Antibodies, Bacterial; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D010958:Plasminogen; D010751:Phosphopyruvate Hydratase