Resistance to P. aeruginosa phenazine toxins requires MDT-15.

(A) Wild-type N2, mdt-15(tm2182) and pmk-1(km25) animals were tested in the toxic phenazine P. aeruginosa pathogenesis assay (also called “fast killing” assay). C. elegans young adult animals were exposed to wild-type (WT) P. aeruginosa, P. aeruginosa carrying a deletion in both of the phenazine biosynthetic operons (Δphz) or E. coli OP50. The difference between mdt-15(tm2182) and N2 animals exposed to P. aeruginosa WT is significant (p<0.001), as is the difference in mdt-15(tm2182) animals exposed to P. aeruginosa WT and P. aeruginosa Δphz (p<0.001). There is no significant difference in pmk-1(km25) animals exposed to P. aeruginosa WT and P. aeruginosa Δphz (p>0.05). This assay is representative of two independent experiments. Figure S6A presents the control condition for this experiment showing that both C. elegans N2 and mdt-15(tm2182) at the L4 stage are sensitive to toxic phenazine-mediated killing (p<0.001). (B) Vector control (L4440), mdt-15(RNAi) and pmk-1(RNAi) animals were exposed to high osmolarity “fast kill” media (pH 5) with E. coli as the food source in the presence or absence of phenazine-1-carboxylic acid and 1-hydroxyphenazine (labeled “toxic phenazines” above) at the approximate concentrations produced by P. aeruginosa under standard assay conditions. The difference in killing between mdt-15(RNAi) animals exposed to toxic phenazines and the other conditions is significant (p<0.001). See also Figure S6. For sample sizes, see Table S3.