Structural model for covalent adhesion of the Streptococcus pyogenes pilus through a thioester bond.
J Biol Chem
; 289(1): 177-89, 2014 Jan 03.
Article
em En
| MEDLINE
| ID: mdl-24220033
ABSTRACT
The human pathogen Streptococcus pyogenes produces pili that are essential for adhesion to host surface receptors. Cpa, the adhesin at the pilus tip, was recently shown to have a thioester-containing domain. The thioester bond is believed to be important in adhesion, implying a mechanism of covalent attachment analogous to that used by human complement factors. Here, we have characterized a second active thioester-containing domain on Cpa, the N-terminal domain of Cpa (CpaN). Expression of CpaN in Escherichia coli gave covalently linked dimers. These were shown by x-ray crystallography and mass spectrometry to comprise two CpaN molecules cross-linked by the polyamine spermidine following reaction with the thioester bonds. This cross-linked CpaN dimer provides a model for the covalent attachment of Cpa to target receptors and thus the streptococcal pilus to host cells. Similar thioester domains were identified in cell wall proteins of other Gram-positive pathogens, suggesting that thioester domains are more widely used and provide a mechanism of adhesion by covalent bonding to target molecules on host cells that mimics that used by the human complement system to eliminate pathogens.
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MEDLINE
Assunto principal:
Streptococcus pyogenes
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Modelos Moleculares
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Fímbrias Bacterianas
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Adesinas Bacterianas
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Multimerização Proteica
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article