Characterization of the collagen-binding S-layer protein CbsA of Lactobacillus crispatus

J. Sillanpaa, B. Martinez, J. Antikainen, T. Toba, N. Kalkkinen, S. Tankka, K. Lounatmaa, J. Keranen, M. Hook, B. Westerlund-Wikstrom, P. H. Pouwels, T. K. Korhonen

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123 Scopus citations


The cbsA gene of Lactobacillus crispatus strain JCM 5810, encoding a protein that mediates adhesiveness to collagens, was characterized and expressed in Escherichia coli. The cbsA open reading frame encoded a signal sequence of 30 amino acids and a mature polypeptide of 410 amino acids with typical features of a bacterial S-layer protein. The cbsA gene product was expressed as a His tag fusion protein, purified by affinity chromatography, and shown to bind solubilized as well as immobilized type I and IV collagens. Three other Lactobacillus S-layer proteins, SIpA, CbsB, and SIpnB, bound collagens only weakly, and sequence comparisons of CbsA with these S-layer proteins were used to select sites in cbsA where deletions and mutations were introduced. In addition, hybrid S-layer proteins that contained the N or the C terminus from CbsA, SIpA, or SIpnB as well as N- and C-terminally truncated peptides from CbsA were constructed by gene fusion. Analysis of these molecules revealed the major collagen-binding region within the N-terminal 287 residues and a weaker type I collagen-binding region in the C terminus of the CbsA molecule. The mutated or hybrid CbsA molecules and peptides that failed to polymerize into a periodic S-layer did not bind collagens, suggesting that the crystal structure with a regular array is optimal for expression of collagen binding by CbsA. Strain JCM 5810 was found to contain another S-layer gene termed cbsB that was 44% identical in sequence to cbsA. RNA analysis showed that cbsA, but not cbsB, was transcribed under laboratory conditions. S-layer-protein-expressing cells of strain JCM 5810 adhered to collagen-containing regions in the chicken colon, suggesting that CbsA-mediated collagen binding represents a true tissue adherence property of L. crispatus.

Original languageEnglish (US)
Pages (from-to)6440-6450
Number of pages11
JournalJournal of bacteriology
Issue number22
StatePublished - 2000

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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