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Bacterial protein domains with a novel Ig‐like fold target human CEACAM receptors
Author(s) -
van Sorge Nina M,
Bonsor Daniel A,
Deng Liwen,
Lindahl Erik,
Schmitt Verena,
Lyndin Mykola,
Schmidt Alexej,
Nilsson Olof R,
Brizuela Jaime,
Boero Elena,
Sundberg Eric J,
van Strijp Jos A G,
Doran Kelly S,
Singer Bernhard B,
Lindahl Gunnar,
McCarthy Alex J
Publication year - 2021
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2020106103
Subject(s) - bacterial adhesin , biology , streptococcus agalactiae , receptor , microbiology and biotechnology , streptococcus , bacteria , escherichia coli , genetics , gene
Streptococcus 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 β protein of GBS binds to human CEACAM1 and CEACAM5 receptors. A crystal structure of the complex showed that an IgSF domain in β 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.