AaaA promotes the ability of <i>P. aeruginosa</i> to respire dipeptides with N-terminal arginine except when adjacent to Arginine or Lysine.

<p><i>P. aeruginosa</i> PAO1 and its derived <i>aaaA</i> deficient mutant were inoculated into nitrogen minimal media (NMM) alone or NMM containing the indicated nitrogen source. Cellular respiration/metabolic activity is reported via reduction of tetrazolium dye and plotted against time. The area under the curve (AUC) for a selection of nitrogen sources following 24 h incubation in each condition is plotted here. The values have been normalised by subtraction of the AUC of the control (no nitrogen source added) on the respective Biolog plate. Relative respiration is calculated by the difference between the normalised AUC of wild type and mutant divided by their sum and multiplied by 100. The fold induction was calculated by dividing the normalised AUC of the mutant by that of the wild type, so a value of 1.0 is no change. Biolog Phenotype microarray plates PM03B and PM06-08 were used as indicated, and each condition performed in duplicate (results from one are shown).