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Crystal structure of Aedes aegypti alanine glyoxylate aminotransferase
Structural highlights
FunctionAGT_AEDAE Catalyzes the pyridoxal 5'-phosphate-dependent transamination of alanine with glyoxylate as an amino group acceptor (PubMed:16681462). Can also catalyze, although with much less efficiency, the transamination of serine, and histidine with glyoxylate and the and transamination of glycine with pyruvate as an amino group acceptor (PubMed:16681462). Does not catalyze the transamination of both 3-hydroxykynurenine and L-kynurenine (PubMed:16681462). May play a role in the detoxification of glyoxylate, a toxic plant metabolite from the pupae and adult diet (Probable).[1] [2] 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 PubMedMosquitoes are unique in having evolved two alanine glyoxylate aminotransferases (AGTs). One is 3-hydroxykynurenine transaminase (HKT), which is primarily responsible for catalyzing the transamination of 3-hydroxykynurenine (3-HK) to xanthurenic acid (XA). Interestingly, XA is used by malaria parasites as a chemical trigger for their development within the mosquito. This 3-HK to XA conversion is considered the major mechanism mosquitoes use to detoxify the chemically reactive and potentially toxic 3-HK. The other AGT is a typical dipteran insect AGT and is specific for converting glyoxylic acid to glycine. Here we report the 1.75A high-resolution three-dimensional crystal structure of AGT from the mosquito Aedes aegypti (AeAGT) and structures of its complexes with reactants glyoxylic acid and alanine at 1.75 and 2.1A resolution, respectively. This is the first time that the three-dimensional crystal structures of an AGT with its amino acceptor, glyoxylic acid, and amino donor, alanine, have been determined. The protein is dimeric and adopts the type I-fold of pyridoxal 5-phosphate (PLP)-dependent aminotransferases. The PLP co-factor is covalently bound to the active site in the crystal structure, and its binding site is similar to those of other AGTs. The comparison of the AeAGT-glyoxylic acid structure with other AGT structures revealed that these glyoxylic acid binding residues are conserved in most AGTs. Comparison of the AeAGT-alanine structure with that of the Anopheles HKT-inhibitor complex suggests that a Ser-Asn-Phe motif in the latter may be responsible for the substrate specificity of HKT enzymes for 3-HK. Crystal structures of Aedes aegypti alanine glyoxylate aminotransferase.,Han Q, Robinson H, Gao YG, Vogelaar N, Wilson SR, Rizzi M, Li J J Biol Chem. 2006 Dec 1;281(48):37175-82. Epub 2006 Sep 21. PMID:16990263[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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