6v3p
The BIgI domain of beta protein from S. agalactiae bound to CEACAM1The BIgI domain of beta protein from S. agalactiae bound to CEACAM1
Structural highlights
FunctionPublication Abstract from PubMedStreptococcus agalactiae, also known as group B Streptococcus (GBS), is the major cause of neonatal sepsis in humans. A critical step to infection is adhesion of bacteria to epithelial surfaces. GBS adhesins have been identified to bind extracellular matrix components and cellular receptors. However, several putative adhesins have no host binding partner characterised. We report here that surface-expressed beta protein of GBS binds to human CEACAM1 and CEACAM5 receptors. A crystal structure of the complex showed that an IgSF domain in beta represents a novel Ig-fold subtype called IgI3, in which unique features allow binding to CEACAM1. Bioinformatic assessment revealed that this newly identified IgI3 fold is not exclusively present in GBS but is predicted to be present in adhesins from other clinically important human pathogens. In agreement with this prediction, we found that CEACAM1 binds to an IgI3 domain found in an adhesin from a different streptococcal species. Overall, our results indicate that the IgI3 fold could provide a broadly applied mechanism for bacteria to target CEACAMs. Bacterial protein domains with a novel Ig-like fold target human CEACAM receptors.,van Sorge NM, Bonsor DA, Deng L, Lindahl E, Schmitt V, Lyndin M, Schmidt A, Nilsson OR, Brizuela J, Boero E, Sundberg EJ, van Strijp JAG, Doran KS, Singer BB, Lindahl G, McCarthy AJ EMBO J. 2021 Apr 1;40(7):e106103. doi: 10.15252/embj.2020106103. Epub 2021 Feb 1. PMID:33522633[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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