FIGURE 1: Alanine catabolism in P. aeruginosa. (A) In the established pathway for alanine catabolism in P. aeruginosa, L-alanine is converted to D-alanine by the DadX racemase. The FAD-dependent D-amino acid dehydrogenase, DadA, then oxidizes D-alanine which results in the generation of pyruvate and ammonia. (B) The proposed role for DadY in the catabolism of alanine by P. aeruginosa is shown. After oxidation of D-alanine at the alpha carbon, DadA releases imino-alanine into the cellular milieu (red, brackets). This α-imine can be deaminated either spontaneously by solvent water (dashed arrow) or by DadY (red), both of which generate the final products, pyruvate and ammonia.