title: Isolation and characterization of a Streptococcus pyogenes protein that binds to basal laminae of human cardiac muscle.
abstract: A 9-kDa glycosaminoglycan-binding protein (GAG-BP) was isolated from Streptococcus pyogenes and purified to homogeneity by affinity chromatography on heparin-agarose. The protein selectively bound to the basal laminae of human cardiac muscle and had an apparent dissociation constant of 2.5 x 10(-7) M. Chemical analyses indicated that the GAG-BP was rich in alanine, lysine, and arginine (pI 9.5) and devoid of tyrosine, methionine, histidine, and half-cystine. There were no detectable carbohydrate or phosphate substituents. The amino acid sequence of the N terminus of GAG-BP showed homology with those of histone-like DNA-binding proteins of several other bacteria. Circular dichroism spectroscopy indicated that the protein was made up of 50% beta-sheet and 50% beta-turn and random coil in aqueous solution; however, when the protein complexed with heparin, it adopted a more ordered structure containing 25% alpha-helix, 50% beta-sheet, and 25% beta-turn and random coil. The GAG-BP cross-reacted serologically with a component of similar size in extracts of other group A streptococci and was present in the culture medium during late logarithmic growth.
authors.affiliation: Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214-3005.
authors.forename: B D
authors.initials: BD
authors.lastname: Winters
authors.forename: N
authors.initials: N
authors.lastname: Ramasubbu
authors.forename: M W
authors.initials: MW
authors.lastname: Stinson
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism; D001485:Basement Membrane / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D002942:Circular Dichroism; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D011817:Rabbits; D013297:Streptococcus pyogenes / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D002352:Carrier Proteins; C082315:GAG-BP protein, Streptococcus pyogenes; D006025:Glycosaminoglycans