Fig. 3: LD1,3-crosslinking activity.
A In vitro activity assays of LDTBcn on M4-rich peptidoglycan sacculi from V. cholerae vs control (no enzyme added). LD1,3-crosslinked muropeptides are labeled in green and the products of LDTBcn endopeptidase activity are labeled in blue. B Muropeptide quantifications from panel (A). Variation is calculated as the difference in relative molar abundance of the muropeptide in the LDTBcn treated reaction minus control reaction in the in vitro assays. Relative molar abundances were calculated as the percentage of the peak area of a muropeptide, divided by its molecular weight, compared to the sum of peak areas in the chromatogram. C Effect of Ampicillin 100 µg/ml (Amp), Imipenem 100 µg/ml (Imp) and copper 1 mM (Cu2+) on the in vitro assays shown in panel (A). nd: not detected. D Scheme and in vitro activity assays of LDTBcn on M4-rich peptidoglycan sacculi previously modified with incorporated D-Met at the terminal position of the tetrapeptides. KP27 endopeptidase cleaving between L-Ala1 and D-Glu2 was used as control. Left side, UV muropeptide profiles of the mutanolysin-digested insoluble pellets showing the presence of D-Met modified muropeptides (in red), endopeptidase products (M1 and M1-M1, in blue) and LD1,3-crosslinked muropeptides (in green). The MS extracted ion chromatogram (XIC) trace of the D-Met containing tripeptide (E-mDAP-M) in the soluble fraction is shown on the right side. Error bars in graphs (B, C) represent standard deviation from mean. Source data for (B, C) are provided as a Source Data file.
