This entry comprises two domains found in the nitrogen regulatory protein NrpR that bind DNA and repress transcription of nitrogen assimilation genes. The two NrpR regulatory domains (NRD1 and NRD2) that sense and bind 2-oxoglutarate (2OG) are both structurally and functionally homologous and share a high degree of sequence conservation. Mutational analysis of NrpR from Methanococcus maripaludis (MmNrpR) indicated that the two most critical residues for 2OG binding are Cys389 and His435 (Cys395 and His441, respectively in thermophilic archaeon Methanocaldococcus jannaschii (MjNrpR)). Both the Cys395 and His441 are conserved among NrpR proteins from diverse species [1].

1: Structural underpinnings of nitrogen regulation by the prototypical nitrogen-responsive transcriptional factor NrpR. Wisedchaisri G, Dranow DM, Lie TJ, Bonanno JB, Patskovsky Y, Ozyurt SA, Sauder JM, Almo SC, Wasserman SR, Burley SK, Leigh JA, Gonen T; Structure. 2010;18:1512-1521. PMID:21070950