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Structure of the C-terminal domain of AspA (antigen I/II-family) protein from Streptococcus pyogenes
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Medicine, Department of Odontology, School of Dentistry.
University of Bristol.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2014 (English)In: FEBS open Bio, ISSN 2211-5463, Vol. 4, 283-289 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 4, 283-289 p.
Keyword [en]
crystal structure, adhesin, streptococci, isopeptide
National Category
Structural Biology
Research subject
biological chemistry; Biochemistry
URN: urn:nbn:se:umu:diva-79210DOI: 10.1016/j.fob.2014.02.012OAI: diva2:640267
Swedish Research Council, 2011-4186
Available from: 2013-08-13 Created: 2013-08-13 Last updated: 2014-06-16Bibliographically approved
In thesis
1. Structural and functional studies of streptococcal surface adhesins
Open this publication in new window or tab >>Structural and functional studies of streptococcal surface adhesins
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The oral cavity is home to an array of microorganisms that are associated with dental plaque. Some Gram-positive bacteria are common inhabitants of the oral cavity and in order to colonize such a unique environment adhesion becomes essential and is accomplish by adhesins expressed on the bacterial surface. Adhesins can interact with host molecules or with structures on the resident oral microbial flora. Members of the antigen I/II (AgI/II) protein family are commonly found on the surface of oral streptococci and have the unique feature that their putative adhesin domain is located in the centre of the primary sequence. Crystal structures representing parts of the C-terminal domains from two AgI/II members, SpaP from Streptococcus mutans and AspA from Streptococcus pyogenes, were determined to 2.2 and 1.8 Å resolution respectively. The structures are very similar and consist of two domains with DEv-IgG folds. The proteins are stabilized by intramolecular isopeptide bonds and tightly coordinated metal ions.

Another group of surface proteins is the microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) that have their putative adhesin domain in the N-terminal, presented on a stalk formed by multiples of repeated C-terminal domains. Sgo0707 from Streptococcus gordonii is an example of this group of proteins and its N-terminal domain was determined to 2.1 Å resolution. The structure consists of two domains, N1 and N2, both of which adopt β-sandwiches. In the Sgo0707 structure no isopeptide bonds or metal ions were detected. A putative binding cleft is present in the N1 domain. Functional studies revealed collagen type-1 and keratinocytes as possible binding partners.

In order to further characterize the AgI/II protein AspA from S. pyogenes a long form of the protein, AspA-AVPC, was expressed and purified. During the purification process it was observed that the protein fragmented into two major parts. This process could be inhibited by the addition of 0.5 mM EDTA during protein purification.

In conclusion, these studies have resulted in adding to the knowledge of protein structures and function of streptococcal surface proteins.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2013. 41 p.
Umeå University odontological dissertations, ISSN 0345-7532 ; 126
National Category
Structural Biology
urn:nbn:se:umu:diva-78920 (URN)978-7459-689-2 (ISBN)
Public defence
2013-09-12, Sal 9D, Tandläkarhögskolan 9 tr, Norrlands universitetssjukhus, Umeå, 10:00 (English)
Available from: 2013-08-15 Created: 2013-07-25 Last updated: 2013-09-27Bibliographically approved

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Hall, MichaelNylander, ÅsaPersson, Karina
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