title: Structure of the C-terminal domain of AspA (antigen I/II-family) protein from Streptococcus pyogenes.
abstract: The pathogenic bacteria Streptococcus pyogenes can cause an array of diseases in humans, including moderate infections such as pharyngitis (strep throat) as well as life threatening conditions such as necrotizing fasciitis and puerperal fever. The antigen I/II family proteins are cell wall anchored adhesin proteins found on the surfaces of most oral streptococci and are involved in host colonization and biofilm formation. In the present study we have determined the crystal structure of the C2-3-domain of the antigen I/II type protein AspA from S. pyogenes M type 28. The structure was solved to 1.8 Å resolution and shows that the C2-3-domain is comprised of two structurally similar DEv-IgG motifs, designated C2 and C3, both containing a stabilizing covalent isopeptide bond. Furthermore a metal binding site is identified, containing a bound calcium ion. Despite relatively low sequence identity, interestingly, the overall structure shares high similarity to the C2-3-domains of antigen I/II proteins from Streptococcus gordonii and Streptococcus mutans, although certain parts of the structure exhibit distinct features. In summary this work constitutes the first step in the full structure determination of the AspA protein from S. pyogenes.
authors.affiliation: Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Hall
authors.affiliation: Department of Odontology, Division of Oral Microbiology, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Sa
authors.initials: S
authors.lastname: Nylander
authors.affiliation: School of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK.
authors.forename: Howard F
authors.initials: HF
authors.lastname: Jenkinson
authors.affiliation: Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Karina
authors.initials: K
authors.lastname: Persson
keywords: Adhesin; Antigen I/II; Isopeptide bond; X-ray crystallography