Poster Presentation BACPATH 2022

Novel glycosaminoglycan interactions with Group A Streptococcus (#121)

Tahnee B-D. McEwan 1 2 , David M. P. De Oliveira 3 , Lauren Hartley-Tassell 4 , Christopher Day 4 , Emma-Jayne Proctor 1 2 , Victor Nizet 5 , Mark J Walker 3 , Michael Jennings 4 , Ronald Sluyter 1 2 , Martina L. Sanderson-Smith 1 2
  1. Illawarra Health and Medical Research Institute (University of Wollongong), WOLLONGONG, NSW, Australia
  2. Molecular Horizons and School of Chemistry and Molecular Bioscience (University of Wollongong), Wollongong, NSW, Australia
  3. Australian Infectious Diseases Research Centre (University of QLD) , St Lucia, QLD, Australia
  4. Institute for Glycomics (Griffith University), Gold Coast, QLD, Australia
  5. Department of Pediatrics (University of California), San Diego, California, USA

Tissue injury including extracellular matrix (ECM) degradation is a hallmark of group A Streptococcus (GAS) skin infection. Hyaluronic acid, heparan sulfate, heparin, chondroitin sulfate and dermatan sulfate are glycosaminoglycans (GAGs) that are enriched in the cutaneous ECM and have important roles in bacterial colonisation and wound healing. Some GAS M proteins (emm) bind GAGs, but these interactions are not well understood. Previous studies suggest certain emm patterns can also be used as predictors of tissue tropism, such that A-C pattern strains are associated with throat colonisation, D pattern strains are considered skin-tropic, and E pattern strains reveal no tissue site preference. The current study aimed to determine the specificity and affinity of phylogenetically diverse M proteins to GAGs and provide a novel characterisation of GAS-GAG interactions. Initial screening of M protein-GAG binding was achieved using a glycan microarray, and interactions were validated using surface plasmon resonance. Binding of fluorescein-labelled hyaluronic acid, heparin, chondroitin sulfate and dermatan sulfate to GAS strains 5448 (emm1) and ALAB49 (emm53) and their respective isogenic M protein deletion mutants was assessed by flow cytometry. Hyaluronic acid bound all M proteins tested. Heparan sulfate and heparin exclusively interacted with M proteins of A-C and D pattern strains. Chondroitin sulfate preferentially bound M proteins of A-C pattern strains, while dermatan sulfate bound to M proteins associated with all pattern type strains. All fluorescein-labelled GAGs bound whole GAS in an M protein-dependant manner, however deletion of emm53 from ALAB49 did not reduce the number of cells binding heparin despite an overall decrease in fluorescence, indicating other surface receptors may also bind heparin. Novel hyaluronic acid and heparin binding motifs are proposed in the conserved and variable region of M proteins, respectively. We conclude that GAG binding is conserved across GAS M proteins, with evidence of M protein-mediated strain specific interactions.