Download MendeleyA new P(II) protein structure identifies the 2-oxoglutarate binding site.
Truan, D., Huergo, L.F., Chubatsu, L.S., Merrick, M., Li, X.D., Winkler, F.K.(2010) J Mol Biol 400: 531-539
- PubMed: 20493877
- DOI: https://doi.org/10.1016/j.jmb.2010.05.036
- Primary Citation of Related Structures:
3MHY - PubMed Abstract:
P(II) proteins of bacteria, archaea, and plants regulate many facets of nitrogen metabolism. They do so by interacting with their target proteins, which can be enzymes, transcription factors, or membrane proteins. A key feature of the ability of P(II) proteins to sense cellular nitrogen status and to interact accordingly with their targets is their binding of the key metabolic intermediate 2-oxoglutarate (2-OG). However, the binding site of this ligand within P(II) proteins has been controversial. We have now solved the X-ray structure, at 1.4 A resolution, of the Azospirillum brasilense P(II) protein GlnZ complexed with MgATP and 2-OG. This structure is in excellent agreement with previous biochemical data on 2-OG binding to a variety of P(II) proteins and shows that 2-oxoglutarate binds within the cleft formed between neighboring subunits of the homotrimer. The 2-oxo acid moiety of bound 2-OG ligates the bound Mg(2+) together with three phosphate oxygens of ATP and the side chain of the T-loop residue Gln39. Our structure is in stark contrast to an earlier structure of the Methanococcus jannaschii GlnK1 protein in which the authors reported 2-OG binding to the T-loop of that P(II) protein. In the light of our new structure, three families of T-loop conformations, each associated with a distinct effector binding mode and characterized by a different interaction partner of the ammonium group of the conserved residue Lys58, emerge as a common structural basis for effector signal output by P(II) proteins.
Organizational Affiliation:
Macromolecular Crystallography, Swiss Light Source, Villigen PSI, Switzerland.
