Arginine inhibition of the argininosuccinate lyases is conserved among three orders in cyanobacteria

Arginine inhibits the arginine biosynthesis rate-limiting enzyme and leads to the accumulation of intracellular aspartate in Synechocystis sp. PCC 6803

“…These results indicate that Sy ArgG is more sensitively regulated by feedback inhibition than Pp ASSY. This arginine inhibition is similar to that of previously reported arginine biosynthesis enzymes (NAGK and Sy ArgH) in cyanobacteria (Hoare and Hoare 1966 ; Bolay et al 2021 ; Katayama and Osanai 2022 ). Under physiological conditions, the intracellular arginine concentration in Synechocystis 6803 is 0.6 mM (Zhang et al 2018 ).…”

“…Synechocystis 6803 cell crude extract experiments also show that N -acetylornithine aminotransferase activity is 2-fold higher than argininosuccinate synthetase activity (Liu and Yang 2014 ). The k cat / K m of Sy ArgG for the substrate (citrulline: 1.97 s − 1 mM − 1 , aspartate: 2.16 s − 1 mM − 1 ) was lower than that of the last-step enzyme in arginine biosynthesis ( Sy ArgH: 37.3 s − 1 mM − 1 ) (Katayama and Osanai 2022 ). These results indicate that Sy ArgG is the rate-limiting enzyme in arginine biosynthesis.…”

“…In cyanobacteria, N -acetyl-glutamate kinase (NAGK) is a second-step enzyme that is primarily subject to feedback inhibition by arginine during its biosynthesis (Hoare and Hoare 1966 ). Cyanobacterial argininosuccinate lyase (ArgH), the last step of arginine biosynthesis, is also inhibited by arginine, and this inhibition for cyanobacterial ArgH changes with pH (Katayama and Osanai 2022 ). Arginine biosynthesis is also regulated by P II proteins that are widely distributed in bacteria, eukaryotic algae, and plants, and are involved in the regulation of nitrogen assimilation and metabolism (Forchhammer 2004 ).…”