3nek

Publication Abstract from PubMed

Plants and microorganisms reduce environmental inorganic nitrogen to ammonium, which then enters various metabolic pathways solely via conversion of 2-oxoglutarate (2OG) to glutamate and glutamine. Cellular 2OG concentrations increase during nitrogen starvation. We recently identified a family of 2OG-sensing proteins--the nitrogen regulatory protein NrpR--that bind DNA and repress transcription of nitrogen assimilation genes. We used X-ray crystallography to determine the structure of NrpR regulatory domain. We identified the NrpR 2OG-binding cleft and show that residues predicted to interact directly with 2OG are conserved among diverse classes of 2OG-binding proteins. We show that high levels of 2OG inhibit NrpRs ability to bind DNA. Electron microscopy analyses document that NrpR adopts different quaternary structures in its inhibited 2OG-bound state compared with its active apo state. Our results indicate that upon 2OG release, NrpR repositions its DNA-binding domains correctly for optimal interaction with DNA thereby enabling gene repression.

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 Nov 10;18(11):1512-21. PMID:21070950^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.