Bacterial protein domains with a novel Ig-like fold target human CEACAM receptors

Nina M. van Sorge, Daniel A. Bonsor, Liwen Deng, Erik Lindahl, Verena Schmitt, Mykola Lyndin, Alexej Schmidt, Olof R. Nilsson, Jaime Brizuela, Elena Boero, Eric J. Sundberg, Jos A.G. van Strijp, Kelly S. Doran, Bernhard B. Singer, Gunnar Lindahl, Alex J. McCarthy*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)
5 Downloads (Pure)

Abstract

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.

Original languageEnglish
Article numbere106103
Pages (from-to)1-20
JournalEMBO Journal
Volume40
Issue number7
DOIs
Publication statusPublished - 1 Apr 2021

Keywords

  • Adhesin
  • IgI
  • immunoglobulin superfamily
  • receptor
  • Streptococcus agalactiae
  • Streptococcus agalactiae/metabolism
  • Cricetinae
  • Cricetulus
  • Humans
  • Adhesins, Bacterial/chemistry
  • GPI-Linked Proteins/chemistry
  • Animals
  • Cell Adhesion Molecules/chemistry
  • Antigens, CD/chemistry
  • Protein Binding
  • Carcinoembryonic Antigen/chemistry
  • HeLa Cells
  • Binding Sites
  • CHO Cells

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