FIG 3.

NO· causes zinc overload and PDF mismetallation. (A) Free intracellular zinc was measured using a genetically encoded biosensor. WT (blue) or ΔzntA ΔzitB (red) cells were treated with 500 μM spermine NO· for 1 h before measurement of zinc-dependent FRET. Both strains showed an increase in FRET, indicating zinc mobilization by NO·, with higher levels in the ΔzntA ΔzitB efflux-deficient mutant. (B) Peptide deformylase activity in WT extracts (blue) was not significantly different after treatment with 50 μM of the NO· donor spermine NONOate (SperNO) for 1 h, whereas PDF in ΔzntA ΔzitB extracts (red) exhibited an ∼50% loss of activity after NO· treatment. Significance was determined by an unpaired two-tailed t test. *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001; ns, nonsignificant (n = 7). Data are represented as means, with error bars showing standard deviations.