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CRYSTAL STRUCTURE AND MECHANISM OF L-ARGININE: GLYCINE AMIDINOTRANSFERASE: A MITOCHONDRIAL ENZYME INVOLVED IN CREATINE BIOSYNTHESIS
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 PubMedL-arginine:glycine amidinotransferase (AT) catalyses the committed step in creatine biosynthesis by formation of guanidinoacetic acid, the immediate precursor of creatine. We have determined the crystal structure of the recombinant human enzyme by multiple isomorphous replacement at 1.9 A resolution. A telluromethionine derivative was used in sequence assignment. The structure of AT reveals a new fold with 5-fold pseudosymmetry of circularly arranged betabeta alphabeta-modules. These enclose the active site compartment, which is accessible only through a narrow channel. The overall structure resembles a basket with handles that are formed from insertions into the betabeta alphabeta-modules. Binding of L-ornithine, a product inhibitor, reveals a marked induced-fit mechanism, with a loop at the active site entrance changing its conformation accompanied by a shift of an alpha-helix by -4 A. Binding of the arginine educt to the inactive mutant C407A shows a similar mode of binding. A reaction mechanism with a catalytic triad Cys-His-Asp is proposed on the basis of substrate and product bound states. Crystal structure and mechanism of human L-arginine:glycine amidinotransferase: a mitochondrial enzyme involved in creatine biosynthesis.,Humm A, Fritsche E, Steinbacher S, Huber R EMBO J. 1997 Jun 16;16(12):3373-85. PMID:9218780[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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