title: Fibrinogen binding and resistance to phagocytosis of Streptococcus sanguis expressing cloned M protein of Streptococcus pyogenes.
abstract: The biological properties of Streptococcus pyogenes M protein cloned and expressed in S. sanguis were investigated. The spm-5 gene previously cloned into Escherichia coli was subcloned into the E. coli-S. sanguis shuttle plasmid pVA838 to produce a newly constructed plasmid, pBK100. Cells of S. sanguis transformed with pBK100 expressed 53-, 55-, and 58-kilodalton polypeptides reacting with type 5 M protein antiserum in immunoblots. The M protein was expressed on the surface of S. sanguis cells as shown by the capacity of the intact cells to (i) inhibit the reactivity of anti-type 5 antibodies with purified M protein as demonstrated by enzyme-linked immunosorbent assay; (ii) inhibit the opsonization by M5 antisera of type 5 S. pyogenes; (iii) express M-protein-like fibrils on the surface of the organisms that react with M5 antisera as revealed by immunoelectron microscopy; (iv) bind plasma fibrinogen and, as a consequence, resist phagocytosis by human blood neutrophils; and (v) be rendered susceptible to phagocytosis by opsonic M5 antisera. These results provide additional evidence that streptococcal M proteins bind host proteins as a ploy to evade host defense mechanisms.
authors.affiliation: Veterans Administration Medical Center, Memphis, Tennessee.
authors.forename: T P
authors.initials: TP
authors.lastname: Poirier
authors.forename: M A
authors.initials: MA
authors.lastname: Kehoe
authors.forename: E
authors.initials: E
authors.lastname: Whitnack
authors.forename: M E
authors.initials: ME
authors.lastname: Dockter
authors.forename: E H
authors.initials: EH
authors.lastname: Beachey
mesh_terms: D000942:Antigens, Bacterial; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D001770:Blood Bactericidal Activity; D002352:Carrier Proteins; D003001:Cloning, Molecular; D005340:Fibrinogen / Q000502:physiology*; D006801:Humans; D007113:Immunity, Innate; D008565:Membrane Proteins / Q000648:ultrastructure; D010587:Phagocytosis; D010957:Plasmids; D013297:Streptococcus pyogenes / Q000235:genetics*; D013298:Streptococcus sanguis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D014170:Transformation, Genetic
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; C014689:streptococcal M protein; D005340:Fibrinogen