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CRYSTAL STRUCTURE OF HUMAN L-ARGININE:GLYCINE AMIDINOTRANSFERASE IN COMPLEX WITH GAMMA-AMINO BUTYRIC ACID
Structural highlights
DiseaseGATM_HUMAN Defects in GATM are the cause of arginine:glycine amidinotransferase deficiency (AGAT deficiency) [MIM:612718. AGAT deficiency is an autosomal recessive disorder characterized by developmental delay/regression, mental retardation, severe disturbance of expressive and cognitive speech, and severe depletion of creatine/phosphocreatine in the brain. FunctionGATM_HUMAN Catalyzes the biosynthesis of guanidinoacetate, the immediate precursor of creatine. Creatine plays a vital role in energy metabolism in muscle tissues. May play a role in embryonic and central nervous system development. May be involved in the response to heart failure by elevating local creatine synthesis.[1] [2] [3] 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 PubMedHuman L-arginine:glycine amidinotransferase (AT) shows large structural changes of the 300-flap and of helix H9 upon binding of L-arginine and L-ornithine, described as a closed and an open conformation (Humm, A., Fritsche, E., Steinbacher, S., and Huber, R. (1997) EMBO J. 16, 3373-3385). To elucidate the structural basis of these induced-fit movements, the x-ray structures of AT in complex with the amidino acceptor glycine and its analogs gamma-aminobutyric acid and delta-aminovaleric acid, as well as in complex with the amidino donor analogs L-alanine, L-alpha-aminobutyric acid, and L-norvaline, have been solved at 2.6-, 2.5-, 2.37-, 2.3-, 2.5-, and 2.4-A resolutions, respectively. The latter three compounds were found to stabilize the open conformer. The glycine analogs bind in a distinct manner and do not induce the transition to the open state. The complex with glycine revealed a third binding mode, reflecting the rather broad substrate specificity of AT. These findings identified a role for the alpha-amino group of the ligand in stabilizing the open conformer. The kinetic, structural, and thermodynamic properties of the mutants ATDeltaM302 and ATDelta11 (lacks 11 residues of H9) confirmed the key role of Asn300 and suggest that in mammalian amidinotransferases, the role of helix H9 is in accelerating amidino transfer by an induced-fit mechanism. Helix H9 does not add to the stability of the protein. The ligand-induced structural changes of human L-Arginine:Glycine amidinotransferase. A mutational and crystallographic study.,Fritsche E, Humm A, Huber R J Biol Chem. 1999 Jan 29;274(5):3026-32. PMID:9915841[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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