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. 2021 Jun 8;203(13):e00100-21. doi: 10.1128/JB.00100-21

FIG 4.

FIG 4

Zinc chelation inhibits LasB enzymatic activity. (A) Filtered supernatants from 16-h WT, ΔlasA, and ΔlasAB cultures were incubated with 2% azocasein for 15 min. Inset are images showing the ability of WT (i) and ΔlasAB (ii) cell-free supernatants to clear milk plates after 16 h. (B) Filtered supernatants from WT 16 h cultures were left untreated (Control), treated with 50 μM TPEN (TPEN), or treated with 50 μM TPEN and 1 mM ZnSO4 · 7 H2O [TPEN+Zn(II)], (NH4)2Fe(SO4)2 · 6 H2O [TPEN+Fe(II)], or MnCl2 · 4 H2O [TPEN+Mn(II)] for an additional 16 h. Supernatants were then incubated with 2% azocasein for 15 min. The data shown represent the mean ± SD from three independent experiments. (C) Filtered supernatants from WT 16 h cultures were left untreated (Control), treated with 40 μM CP (CP), or treated with 40 μM CP and 1 mM ZnSO4 · 7 H2O [CP+Zn(II)], (NH4)2Fe(SO4)2 · 6 H2O [CP+Fe(II)], or MnCl2 · 4 H2O [CP+Mn(II)] for an additional 16 h. Supernatants were then incubated with 2% azocasein for 15 min. Samples marked with the same letter are not significantly different; samples marked with different letters are significantly different (P < 0.05). An enzyme unit (U) is defined as 1 μmol min−1.