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Group A Streptococcus interacts with glycosaminoglycans via M proteins to modulate bacterial adherence in vitro

Tahnee B-D McEwan1, David M P De Oliveira1,2, Emily K Stares1

  • 1Molecular Horizons and School of Science, University of Wollongong, Wollongong, Australia.

The FEBS Journal
|July 3, 2025
PubMed

Insights

Group A Streptococcus M proteins bind host glycosaminoglycans (GAGs), influencing bacterial skin colonization. Specific GAG interactions, like chondroitin sulfate and dermatan sulfate, enhance bacterial adherence to skin cells.

Area of Science:

  • Microbiology
  • Biochemistry
  • Molecular Biology

Background:

  • Glycosaminoglycans (GAGs) are crucial components of the skin's extracellular matrix, playing a role in bacterial colonization.
  • Group A Streptococcus (GAS) utilizes M proteins as adhesins, which possess lectin-binding properties and interact with host molecules.

Purpose of the Study:

  • To comprehensively profile the specificity and affinity of diverse GAS M proteins for various sulfated host GAGs.
  • To investigate the physiological relevance of these M protein-GAG interactions in bacterial adhesion and colonization.

Main Methods:

  • Surface plasmon resonance was used to analyze M protein-GAG binding kinetics and affinity.
  • Site-directed mutagenesis was employed to identify specific binding sites on M proteins, including the XBXBX motif.
  • Bacterial adherence assays using HaCaT keratinocytes were performed to assess the functional impact of GAG binding.

Main Results:

  • Chondroitin sulfate and dermatan sulfate showed preferential binding to M proteins of A-C pattern strains, with dermatan sulfate binding to all pattern types.
  • Heparin and heparan sulfate exclusively interacted with M proteins from A-C and D pattern strains.
  • M1 protein-expressing GAS strains demonstrated binding to chondroitin sulfate, dermatan sulfate, and heparin, with chondroitin sulfate and dermatan sulfate enhancing bacterial adherence to keratinocytes.

Conclusions:

  • GAS M proteins exhibit diverse binding specificities for host GAGs, impacting bacterial colonization.
  • The interaction of M proteins with specific GAGs, particularly chondroitin sulfate and dermatan sulfate, is critical for enhancing GAS adherence to human keratinocytes.
  • Understanding these molecular interactions provides insights into GAS pathogenesis and infection persistence.
Keywords:
Streptococcus pyogenesepithelial cellsflow cytometryglycan microarraypolysaccharides

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