This domain is found at the C-terminal end of Arginine dihydrolase ArgZ from Synechocystis sp (also known as Sll1336 protein) and similar prokaryotic sequences. ArgZ is involved in an ornithine- ammonia cycle (OAC) in cyanobacteria, which confers substantial adaptability under environmental nitrogen fluctuations. This protein is organised into three domains: a N-terminal domain belonging to the guanidino group-modifying enzyme (GME) family, a middle oxoglutarate reductase/saccharopine dehydrogenase bifunctional enzyme (Pfam:PF04455) and a C-terminal uncharacterized region that can be divided in two subdomains. This entry represents the most C-terminal region, which forms a large Rossmann fold domain. Its specific function is unknown [1].

1: Crystal structures and biochemical analyses of the bacterial arginine dihydrolase ArgZ suggests a "bond rotation" catalytic mechanism. Zhuang N, Zhang H, Li L, Wu X, Yang C, Zhang Y; J Biol Chem. 2020;295:2113-2124. PMID:31914412

2: Structural and mutational analyses of the bifunctional arginine dihydrolase and ornithine cyclodeaminase AgrE from the cyanobacterium Anabaena. Lee H, Rhee S; J Biol Chem. 2020;295:5751-5760. PMID:32198136