Metabolism of Basic Amino Acids in Pseudomonas putida

Abstract Uptake of lysine, arginine, and ornithine by Pseudomonas putida P2 involves at least three transport systems. A lysine-inducible, general basic amino acid system (Km = 7.3 x 10-6 m; Vmax = 128 nmoles per min per mg for l-lysine) transports all three amino acids and is inhibited by the d or l isomers of all three amino acids (Miller, D. L., and Rodwell, V. W. (1971) J. Biol. Chem. 246, 1765) and by the next higher and lower homologs of l-arginine. Transport of l-arginine by the general system (Km = 4.8 x 10-6 m; Vmax = 67 nmoles per min per mg) is inhibited by the same compounds that inhibit l-lysine transport. A second system transports l-lysine (Km = 4.1 x 10-7 m; Vmax = 25 nmoles per min per mg) and l-ornithine (Km = 1.3 x 10-7 m; Vmax = 100 nmoles per min per mg) and is inhibited by d- or l-lysine, d- or l-ornithine, and by d-arginine, but not by l-arginine nor by other amino acids. l-Lysine and l-ornithine accumulate at ratios of intracellular to extracellular amino acid concentration of 750 and 18,000, respectively, suggesting that transport is an active process. Active transport of l-arginine by cells grown on l-arginine occurs via a low Km, l-arginine-specific system (Km = 5.2 x 10-8 m; Vmax = 11 nmoles per min per mg). Transport, which is not inhibited by any substrate analog tested, is linear for at least 7 min, is abolished by CN- or N3-, and generates ratios of internal to external arginine as high as 3350.