Figure 3. Water-forming NADH oxidase (NOX) restores redox homeostasis in respiration-deficient L. monocytogenes strains.

(A) Reaction catalyzed by the Lactococcus lactis water-forming NOX, which is the same as aerobic respiration without the generation of a proton motive force. (B) NAD⁺/NADH ratios of parent and NOX-complemented L. monocytogenes strains grown aerobically in nutrient-rich media to mid-logarithmic phase. Results from three independent experiments are presented as means and standard deviations. Statistical significance was calculated using one-way ANOVA and Dunnett’s post-test using the wildtype parent strain as the control. ****, p<0.0001; ***, p<0.001; **, p<0.01; ns, not statistically significant (p>0.05). (C) Fermentation products of L. monocytogenes strains grown in nutrient-rich media under aerobic conditions. Error bars show standard deviations. Results from three independent experiments are shown. ΔQC, ΔqoxA/ΔcydAB; ΔQC/fmnB, ΔqoxA/ΔcydAB/fmnB::tn; + NOX, strains complemented with L. lactis nox.

Figure 3—figure supplement 1. NOX expression in respiration-deficient mutants fails to rescue swarming motility.

The swarming motility of parent and NOX-complemented Listeria monocytogenes strains is shown as a percentage relative to the wildtype swarming diameter following 48 hours incubation at 30°C. Error bars represent standard deviations of the mean swarming diameters from three independent experiments. Statistical significance between the wildtype and mutant strains was calculated using one-way ANOVA and unpaired two-tailed t test was utilized to determine significance between parent and NOX-complemented strains. ****, p<0.0001; ***, p<0.001; **, p<0.01; *, p<0.05; ns, no significant difference (p>0.05).