Two intramolecular isopeptide bonds are identified in the crystal structure of the Streptococcus gordonii SspB c-terminal domain
2010 (English)In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 397, no 3, 740-751 p.Article in journal (Refereed) Published
Streptococcus gordonii is a primary colonizer and is involved in the formation of dental plaque. This bacterium expresses several surface proteins. One of them is the adhesin SspB, which is a member of the Antigen I/II family of proteins. SspB is a large multi-domain protein that has interactions with surface molecules on other bacteria and on host cells, and is thus a key factor in the formation of biofilms. Here, we report the crystal structure of a truncated form of the SspB C-terminal domain, solved by single-wavelength anomalous dispersion to 1.5Å resolution. The structure represents the first of a C-terminal domain from a streptococcal Antigen I/II protein and is comprised of two structurally related β-sandwich domains, C2 and C3, both with a Ca2+ bound in equivalent positions. In each of the domains, a covalent isopeptide bond is observed between a lysine and an asparagine, a feature that is believed to be a common stabilization mechanism in Gram-positive surface proteins. S. gordonii biofilms contain attachment sites for the periodontal pathogen Porphyromonas gingivalis and the SspB C-terminal domain has been shown to have one such recognition motif, the SspB adherence region. The motif protrudes from the protein, and serves as a handle for attachment. The structure suggests several additional putative binding surfaces, and other binding clefts may be created when the fulllength protein is folded.
Place, publisher, year, edition, pages
Academic Press, 2010. Vol. 397, no 3, 740-751 p.
crystal structure, X-ray crystallography, protein structure, surface adhesin, isopeptide bond
Dentistry Structural Biology Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Research subject Biochemistry; Odontology
IdentifiersURN: urn:nbn:se:umu:diva-32907DOI: 10.1016/j.jmb.2010.01.065ISI: 000276177300010PubMedID: 20138058OAI: oai:DiVA.org:umu-32907DiVA: diva2:306651