A Novel Virulence Strategy for Pseudomonas aeruginosa Mediated by an Autotransporter with Arginine-Specific Aminopeptidase Activity
Figure 4
AaaA can remove arginine from p-nitroanilide.
Panel A. The P. aeruginosa ΔaaaA mutant alone (open triangles) or bearing either the empty plasmid pME6032 (open circles) or its derivative carrying aaaA (pME6032::aaaA: closed circles) were treated as described in Figure S2B except arginine-p-nitroanilide was used as a substrate. WT PAO1 cells were treated similarly (closed triangles), and activities (measured as changes in A405 nm) are compared against a growth media blank (crosses). Panel B. E. coli DH5α bearing either the empty plasmid pME6032 (open circles) or its derivative carrying aaaA (pME6032::aaaA: closed circles) were grown in LB until exponential phase, induced with 1 mM IPTG, and then incubated with arginine-p-nitroanilide as described in Figure S2B. Activities are compared against a growth media blank (crosses). Error bars are+/−1 S.D. (n = 15). All measurements have been corrected for differential growth of bacteria by normalising to an initial OD600 nm of 0.1.