Fig. 4: Regulation of the enzymatic activity of LmPC-PLC by the N-terminal W1 and the propeptide added in trans.
a W1 (sticks) in the active site of LmPC-PLC, molB. Interactions between W1 and other residues and Fe3 are shown as dotted gray lines. Zn (position 1) and Fe (positions 2 and 3) ions: numbered violet (Zn) and brown (Fe) spheres. b Activity of the W1 mutants (50 nM) relative to WT LmPC-PLC towards 100% POPC MLVs (4.5 mM). c Activity of W1 mutants (500 nM) relative to WT LmPC-PLC towards 4-NPPC (1 mM). d Top: Amino-acid sequence of the LmPC-PLC propeptide (highlighted in pink), and the synthetic peptides NE6 and NS-26 used in assays. Bottom: Dose-dependent inhibition of LmPC-PLC (500 nM) by the two peptides towards 4-NPPC (1 mM). e Inhibition of activity of PC-PLC homologs (500 nM) by the two peptides (100 μM) on 4-NPPC (1 mM). f Inhibition of activity of PC-PLC homologs (50 nM) by the two peptides (10 μM), on 100% POPC MLVs (4.5 mM). g Inhibition of LmPC-PLC cysteine mutants (500 nM) towards 4-NPPC (1 mM) by the two peptides (100 μM) in comparison with WT LmPC-PLC (500 nM). h Inhibition of LmPC-PLC cysteine mutants (50 nM) on 100% POPC MLVs (4.5 mM) by the peptides (10 μM) in comparison to the WT LmPC-PLC (50 nM). Experiments were performed in 20 mM MES pH 6.5, 150 mM NaCl, 50 (b, f, h) or 500 μM (c, d, e, g) ZnSO4, and 1 mM CaCl2 (only for Cp) at 37 °C. Dunnett’s multiple comparisons test was performed (b, c, e–h), ns: P > 0.05, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. n = 3 independent experiments (b–h). Data (b–h) are presented as mean values ± SEM. Source data are provided as a Source Data file.
