FIG 1.

Schematic of ATP and NH₄⁺ generation through the arginine deiminase (ADI) pathway. Arginine is transported into the cell through an arginine/ornithine antiporter (ArcD). Arginine deiminase (ArcA) and ornithine carbamoyltransferase (ArcB) subsequently catalyze the formation of citrulline and carbamoyl phosphate/ornithine, respectively. Carbamate kinase (ArcC) catalyzes the formation of CO₂, ATP, and NH₄⁺ from carbamoyl phosphate, whereas ornithine is exported from the cell, facilitating the import of arginine.