3rex

Crystal structure of the archaeal asparagine synthetase A complexed with Adenosine monophosphate

spinqualitylabelsall models 3rex, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3rex is a 2 chain structure with sequence from Pyrococcus abyssi. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: AMP, MG Related: 1nnh, 3p8t, 3p8v, 3p8y, 3reu Gene: asnS-like, PYRAB02460, PAB2356 (Pyrococcus abyssi) Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Asparagine synthetase A (AsnA) catalyzes asparagine synthesis using aspartate, ATP, and ammonia as substrates. Asparagine is formed in two steps: the beta-carboxylate group of aspartate is first activated by ATP to form an aminoacyl-AMP before its amidation by a nucleophilic attack with an ammonium ion. Interestingly, this mechanism of amino acid activation resembles that used by aminoacyl-tRNA synthetases, which first activate the alpha-carboxylate group of the amino acid to form also an aminoacyl-AMP before they transfer the activated amino acid onto the cognate tRNA. In a previous investigation, we have shown that the open reading frame of Pyrococcus abyssi annotated as asparaginyl-tRNA synthetase (AsnRS) 2 is, in fact, an archaeal asparagine synthetase A (AS-AR) that evolved from an ancestral aspartyl-tRNA synthetase (AspRS). We present here the crystal structure of this AS-AR. The fold of this protein is similar to that of bacterial AsnA and resembles the catalytic cores of AspRS and AsnRS. The high-resolution structures of AS-AR associated with its substrates and end-products help to understand the reaction mechanism of asparagine formation and release. A comparison of the catalytic core of AS-AR with those of archaeal AspRS and AsnRS and with that of bacterial AsnA reveals a strong conservation. This study uncovers how the active site of the ancestral AspRS rearranged throughout evolution to transform an enzyme activating the alpha-carboxylate group into an enzyme that is able to activate the beta-carboxylate group of aspartate, which can react with ammonia instead of tRNA. Crystal Structure of the Archaeal Asparagine Synthetase: Interrelation with Aspartyl-tRNA and Asparaginyl-tRNA Synthetases.,Blaise M, Frechin M, Olieric V, Charron C, Sauter C, Lorber B, Roy H, Kern D J Mol Biol. 2011 Sep 23;412(3):437-52. Epub 2011 Jul 28. PMID:21820443 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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