Involved in the anabolism of D-lysine and D-arginine. Under aerobic conditions, the arginine succinyltransferase (AST) and arginine transaminase (ATA) pathways are 2 major routes for L-arginine utilization as the sole source of carbon and nitrogen. The D-to-L racemization of arginine by DauA and DauB is necessary, before to be channeled into the AST and/or ATA pathways. DauB catalyzes the synthesis of L-arginine from 2-ketoarginine (2-KA) and ammonium. H2O + L-arginine + NAD(+) = 5-guanidino-2-oxopentanoate + H(+) + NADH + NH4(+) H2O + L-arginine + NADP(+) = 5-guanidino-2-oxopentanoate + H(+) + NADPH + NH4(+) Induced by growth on D-arginine and D-lysine. Repressed by DauR (PubMed:19139398). ArgR could be a transcriptional activator of the dauBAR operon in response to the presence of L-Arg (PubMed:19850617). Cells lacking this gene grow similarly to the wild-type on D-Arg or D-Lys as sole nitrogen source, but are unable to grow on D-Arg as sole carbon source. Belongs to the ornithine cyclodeaminase/mu-crystallin family.