Transport of basic amino acids by the dinitrogen-fixing cyanobacterium Anabaena PCC 7120.
Two transport systems for L-arginine were evident in Anabaena sp. strain PCC 7120: a high-affinity one (Km, 1.7 microM) that accumulated arginine within the cells through an energy-requiring process and another one that exhibited low affinity for L-arginine (Km, 0.75 mM) and was unable to accumulate the substrate. Both systems were inhibited by L-canavanine, L-lysine, and L-ornithine. Two systems were also evident for L-lysine uptake (Km, 1.9 and 110 microM, respectively). After selection for resistance to canavanine or hydroxylysine, independent mutants were isolated which were impaired in the high-affinity uptake of arginine and lysine. A common permease appears, therefore, to be involved in the high-affinity transport of these basic amino acids. Both the high- and the low-affinity systems can contribute to the growth of Anabaena sp. on L-arginine. However, arginine did not effectively repress either nitrogenase or nitrate reductase.
Herrero
A
A
Instituto de Bioquímica Vegetal y Fotosintesis, Universidad de Sevilla, Spain.
Flores
E
E
D000599:Amino Acids, Diamino / Q000378:metabolism* / Q000494:pharmacology; D001120:Arginine / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D007700:Kinetics; D009154:Mutation; D009586:Nitrogen Fixation
D000599:Amino Acids, Diamino; D004024:Dicyclohexylcarbodiimide; D001120:Arginine