10.6084/m9.figshare.5120620.v1 Lauth X. Lauth X. von Köckritz-Blickwede M. von Köckritz-Blickwede M. McNamara C.W. McNamara C.W. Myskowski S. Myskowski S. Zinkernagel A.S. Zinkernagel A.S. Beall B. Beall B. Ghosh P. Ghosh P. Gallo R.L. Gallo R.L. Nizet V. Nizet V. Supplementary Material for: M1 Protein Allows Group A Streptococcal Survival in Phagocyte Extracellular Traps through Cathelicidin Inhibition Karger Publishers 2009 Group A Streptococcus Streptococcus pyogenes Virulence factor Innate immunity M protein Neutrophil Mast cell Extracellular traps Antimicrobial peptide Cathelicidin 2009-02-20 00:00:00 Dataset https://karger.figshare.com/articles/dataset/Supplementary_Material_for_M1_Protein_Allows_Group_A_Streptococcal_Survival_in_Phagocyte_Extracellular_Traps_through_Cathelicidin_Inhibition/5120620 M1 protein contributes to Group A <i>Streptococcus</i> (GAS) systemic virulence by interfering with phagocytosis and through proinflammatory activities when released from the cell surface. Here we identify a novel role of M1 protein in the stimulation of neutrophil and mast cell extracellular trap formation, yet also subsequent survival of the pathogen within these DNA-based innate defense structures. Targeted mutagenesis and heterologous expression studies demonstrate M1 protein promotes resistance to the human cathelicidin antimicrobial peptide LL-37, an important effector of bacterial killing within such phagocyte extracellular traps. Studies with purified recombinant protein fragments mapped the inhibition of cathelicidin killing to the M1 hypervariable N-terminal domain. A survey of GAS clinical isolates found that strains from patients with necrotizing fasciitis or toxic shock syndrome were significantly more likely to be resistant to cathelicidin than GAS M types not associated with invasive disease; M1 isolates were uniformly resistant. We conclude increased resistance to host cathelicidin and killing within phagocyte extracellular traps contribute to the propensity of M1 GAS strains to produce invasive infections.