1w7n
Crystal structure of human kynurenine aminotransferase I in PMP form
Structural highlights
FunctionKAT1_HUMAN Catalyzes the irreversible transamination of the L-tryptophan metabolite L-kynurenine to form kynurenic acid (KA). Metabolizes the cysteine conjugates of certain halogenated alkenes and alkanes to form reactive metabolites. Catalyzes the beta-elimination of S-conjugates and Se-conjugates of L-(seleno)cysteine, resulting in the cleavage of the C-S or C-Se bond.[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 PubMedThe kynurenine pathway has long been regarded as a valuable target for the treatment of several neurological disorders accompanied by unbalanced levels of metabolites along the catabolic cascade, kynurenic acid among them. The irreversible transamination of kynurenine is the sole source of kynurenic acid, and it is catalyzed by different isoforms of the 5'-pyridoxal phosphate-dependent kynurenine aminotransferase (KAT). The KAT-I isozyme has also been reported to possess beta-lyase activity toward several sulfur- and selenium-conjugated molecules, leading to the proposal of a role of the enzyme in carcinogenesis associated with environmental pollutants. We solved the structure of human KAT-I in its 5'-pyridoxal phosphate and pyridoxamine phosphate forms and in complex with the competing substrate l-Phe. The enzyme active site revealed a striking crown of aromatic residues decorating the ligand binding pocket, which we propose as a major molecular determinant for substrate recognition. Ligand-induced conformational changes affecting Tyr(101) and the Trp(18)-bearing alpha-helix H1 appear to play a central role in catalysis. Our data reveal a key structural role of Glu(27), providing a molecular basis for the reported loss of enzymatic activity displayed by the equivalent Glu --> Gly mutation in KAT-I of spontaneously hypertensive rats. Crystal structure of human kynurenine aminotransferase I.,Rossi F, Han Q, Li J, Li J, Rizzi M J Biol Chem. 2004 Nov 26;279(48):50214-20. Epub 2004 Sep 10. PMID:15364907[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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