Change search
ReferencesLink to record
Permanent link

Direct link
A crystallizable form of the Streptococcus gordonii surface antigen SspB C-domain obtained by limited proteolysis
Umeå University, Faculty of Medicine, Odontology, Cariology. (Karina Persson)
Umeå University, Faculty of Medicine, Odontology. (Karina Persson)
2009 (English)In: Acta Crystallographica. Section F: Structural Biology and Crystallization Communications, ISSN 1744-3091, E-ISSN 1744-3091, Vol. 65, no 7, 712-714 p.Article in journal (Refereed) Published
Abstract [en]

SspB is a 1500-residue adhesin expressed on the surface of the oral bacterium Streptococcus gordonii. Its interaction with other bacteria and host cells initiates the development of dental plaque. The full-length C-terminal domain of SspB was cloned, overexpressed in Escherichia coli and purified. However, the protein could not be crystallized. Limited proteolysis of the full-length C-domain identified a core fragment. The proteolysis product was cloned, expressed and purified. The protein was crystallized using the hanging-drop vapour-diffusion method. X-ray data were collected and processed to a maximum resolution of 2.1 A with 96.4% completeness. The crystals belonged to space group P2(1), with one molecule in the asymmetric unit, a solvent content of 33.7% and a corresponding Matthews coefficient of 1.85 A(3) Da(-1).

Place, publisher, year, edition, pages
2009. Vol. 65, no 7, 712-714 p.
Keyword [en]
protein crystal, limited proteolysis, adhesin
National Category
Dentistry Dentistry
Research subject
Odontology; Molecular Biology
URN: urn:nbn:se:umu:diva-26212DOI: 10.1107/S1744309109021046PubMedID: 19574647OAI: diva2:240857
Available from: 2009-10-13 Created: 2009-09-30 Last updated: 2010-04-01Bibliographically approved
In thesis
1. Structural studies of the surface adhesin SspB from Streptococcus gordonii
Open this publication in new window or tab >>Structural studies of the surface adhesin SspB from Streptococcus gordonii
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Surface proteins on microorganisms that build up the oral biofilm are key players in the formation of the biofilm. Antigen I/II proteins are surface adhesins found on virtually all oral streptococci and share a conserved multi-domain architecture. These adhesins bind surface components on other bacteria and on host cells. Thus, they are crucial for the development of the biofilm.    

The objective of this thesis work is the structural characterization of the large multi-domain Antigen I/II protein SspB from the primary colonizing commensal bacterium Streptococcus gordonii.

The crystal structure of the variable domain of SspB was determined to 2.3 Å resolution. The domain comprises a β-supersandwich and a putative binding cleft stabilized by a calcium ion. Despite high similarity in the overall structure, the cleft within SspB is significantly smaller than the cleft within the homologous protein from Streptococcus mutans, indicating that different substrates may bind in the clefts. A screen for carbohydrate binding resulted in no hits for interaction with the SspB variable domain suggesting that the cleft may not be suitable for binding sugars.

This thesis also presents the high resolution 1.5 Å structure of a truncated C-terminal domain of SspB, the first of an Antigen I/II C-domain. The structure contains two structurally related domains, each containing one calcium ion and one intramolecular isopeptide bond. The SspB protein shares the feature of intramoleular isopeptide bonds with other surface proteins from Gram positive bacteria, such as pili from Streptococcus pyogenes and Corynebacterium diphtheriae. Intramolecular isopeptide bonds are suggested to be a common feature for retaining stability in a harsh environment. The SspB adherence region, shown to be the recognition motif for Porphyromonas gingivalis attachment to S. gordonii, protrudes from the core protein as a handle available for recognition.

In conclusion, this thesis work has provided new knowledge about the SspB protein and increased the understanding of the common structure of AgI/II proteins.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2010. 41 p.
Umeå University odontological dissertations, ISSN 0345-7532 ; 111
Streptococcus gordonii, X-ray crystallography, surface adhesin, dental plaque, structural biology
National Category
Structural Biology Dentistry
Research subject
urn:nbn:se:umu:diva-32910 (URN)978-91-7264-955-2 (ISBN)
Public defence
2010-04-23, Sal D, By 1D, Tandläkarhögskolan, NUS, Umeå, 13:00 (English)
Available from: 2010-04-01 Created: 2010-03-30 Last updated: 2010-04-01Bibliographically approved

Open Access in DiVA

fulltext(324 kB)262 downloads
File information
File name FULLTEXT01.pdfFile size 324 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Forsgren, NinaPersson, Karina
By organisation
In the same journal
Acta Crystallographica. Section F: Structural Biology and Crystallization Communications

Search outside of DiVA

GoogleGoogle Scholar
Total: 262 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 124 hits
ReferencesLink to record
Permanent link

Direct link