FIG 4.

DpaA is active against TetraGly4 and TetraTetraGly4. (A) PG from an araBplptC ΔdpaA (+arabinose) strain was incubated with DpaA at pH 5.0 or 7.5, followed by digestion with cellosyl and analysis of the muropeptide composition by HPLC. In addition to its expected decrease of Tri-LysArg, DpaA was also active against muropeptides containing glycine at position 4 (muropeptides 2 and 5). DpaA showed higher activity against TetraGly4 and TetraTetraGly4 at acidic pH. Chromatographs were cropped at 250 mAU to better observe the minor muropeptides. (B) Structures of the relevant muropeptide labeled in panel A. Figure S2C shows that DpaA is not active against muropeptides with noncanonical d-amino acids at position 4 of the PG stem peptide. Muropeptides names are according to the work of Glauner et al. (14).