Genes and Enzymes of Lysine Catabolism in Pseudomonas aeruginosa

Pseudomonas aeruginosa strain PAO1 cannot utilize L-lysine effectively as a carbon source for growth but grows on cadaverine and glutarate. Strains PAO1 and PAO1632 (Hut-Ami-) have low activities for L-lysine uptake and for L-lysine decarboxylase but both strains gave rise to mutants that grew well on L-lysine. Strain PAO2087, isolated from PAO1, had an active L-lysine uptake system and an inducible L-lysine decarboxylase. Strain PAO2070, isolated from strain PAO1632, had an active L-lysine uptake system and a constitutive L-lysine decarboxylase. We suggest that the genetic defect of strain PAO1 (and PAO1632) that prevents growth of L-lysine is in a regulatory gene controlling the expression of linked genes for L-lysine permease and L-lysine decarboxylase. Mutants unable to utilize L-lysine as a carbon source, isolated from strain PAO2070, exhibited four distinct growth phenotypes. Transductional analysis showed that the genetic defects of these mutants could be distinguished from each other and from that of strain PAO1. Group I mutants, unable to utilize glutarate, formed a single transduction linkage group and were mapped at about 20 min on the chromosome. The mutations of groups II, III and IV appeared to be in separate but linked genes. The group II mutants had no detectable L-lysine decarboxylase activity and the gene locus was mapped by interrupted mating in the 50 to 60 min region of the chromosome. The group III mutants possessed all the early enzymes of the L-lysine decarboxylase pathway and lacked only an active L-lysine uptake system.