2j9c
Structure of GlnK1 with bound effectors indicates regulatory mechanism for ammonia uptakeStructure of GlnK1 with bound effectors indicates regulatory mechanism for ammonia uptake
Structural highlights
FunctionGLNK1_METJA Involved in the regulation of nitrogen metabolism (PubMed:17203075). Regulates the activity of its targets by protein-protein interaction in response to the nitrogen status of the cell (PubMed:17203075). Regulates the activity of the ammonia channel Amt1 via direct interaction (PubMed:17203075).[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA binary complex of the ammonia channel Amt1 from Methanococcus jannaschii and its cognate P(II) signalling protein GlnK1 has been produced and characterized. Complex formation is prevented specifically by the effector molecules Mg-ATP and 2-ketoglutarate. Single-particle electron microscopy of the complex shows that GlnK1 binds on the cytoplasmic side of Amt1. Three high-resolution X-ray structures of GlnK1 indicate that the functionally important T-loop has an extended, flexible conformation in the absence of Mg-ATP, but assumes a compact, tightly folded conformation upon Mg-ATP binding, which in turn creates a 2-ketoglutarate-binding site. We propose a regulatory mechanism by which nitrogen uptake is controlled by the binding of both effector molecules to GlnK1. At normal effector levels, a 2-ketoglutarate molecule binding at the apex of the compact T-loop would prevent complex formation, ensuring uninhibited ammonia uptake. At low levels of Mg-ATP, the extended loops would seal the ammonia channels in the complex. Binding of both effector molecules to P(II) signalling proteins may thus represent an effective feedback mechanism for regulating ammonium uptake through the membrane. Structure of GlnK1 with bound effectors indicates regulatory mechanism for ammonia uptake.,Yildiz O, Kalthoff C, Raunser S, Kuhlbrandt W EMBO J. 2007 Jan 24;26(2):589-99. Epub 2007 Jan 4. PMID:17203075[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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