D lysine catabolic pathway in Pseudomonas putida: interrelations with L lysine catabolism

Abstract

The isolation of several mutant strains blocked in L-lysine degradation has permitted an assessment of the physiological significance of enzymatic reactions related to lysine metabolism in Pseudomonas putida. Additional studies with intact cells involved labeling of metabolic intermediates from radioactive L- or D-lysine, and patterns of enzyme induction in both wild type and mutant strains. These studies lead to the conclusions that from L-lysine, the obligatory pathway is via δ-aminovaleramide, δ-aminovalerate, glutaric semialdehyde, and glutarate, and that no alternative pathways from L-lysine exist in this strain. A distinct pathway from D-lysine proceeds via Δ1 piperideine 2 carboxylate, L-pipecolate, and Δ1 piperideine 6 carboxylate (α-aminoadipic semialdehyde). The two pathways are independent in the sense that certain mutants, unable to grow on L-lysine, grow at wild type rates of D-lysine, utilizing the same intermediates as the wild type, as inferred from labeling studies. Pipecolate oxidase, a D-lysine related enzyme, is induced by D-lysine and less efficiently by L-lysine. Aminooxyacetate virtually abolishes the inducing activity of L-lysine for this enzyme. Enzymatic studies are reported which implicate Δ1 piperideine 2 carboxylate, reductase as an early step in the D-lysine pathway.