Fig. 1: Analysis of GAC released from the GAS cell wall by chemical treatments.

a Molecular model illustrating GAC covalently attached to peptidoglycan via a phosphodiester bond. GAC contains a → 3)α-Rha(1 → 2)α-Rha(1 → repeating backbone. The β-GlcNAc side-chains are linked to the 3 position of the α-1,2-linked Rha^95,96. Phosphate groups in GAC are involved in the phosphodiester bond linking glycerol to the GlcNAc side-chain and the GAC reducing terminal sugar residue to peptidoglycan¹⁵. b Release of GAC from GAS cell wall by mild acid hydrolysis or HONO deamination, before and after chemical N-acetylation. The treatment conditions are indicated by gray rectangles below the bar graph. c Release of GAC from GAS sacculi by mild acid hydrolysis, before (left) and after (right) chemical N-acetylation. d Release of GAC from GAS sacculi by HONO deamination, before (left) and after (right) chemical N-acetylation. In b–d the concentration of GAC released from the sacculi was estimated by the modified anthrone assay described in “Methods” and normalized to total GAC content in sacculi. Symbols and error bars represent the mean and S.D., respectively (n = 3 biologically independent replicates). Data are mean values ± S.D., n = 3 biologically independent experiments. In b P values were calculated by one-way ANOVA with Tukey’s multiple comparisons test. In c, d P values were calculated by two-way ANOVA with Tukey’s multiple comparisons test. Source data for b–d are provided as a Source data file.