1upb
Carboxyethylarginine synthase from Streptomyces clavuligerus
Structural highlights
FunctionCEAS_STRCL Involved in the biosynthesis of the beta-lactamase inhibitor, clavulanic acid. Catalyzes the thiamine diphosphate (ThDP) dependent condensation of D-glyceraldehyde-3-phosphate (D-G3P) with L-arginine to yield the beta-amino acid, N2-(2-carboxyethyl)arginine (CEA) via a beta-elimination resulting in the formation of an enol which undergoes a second elimination to generate the alpha,beta-unsaturated acryloyl-ThDP.[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 PubMedThe initial step in the biosynthesis of the clinically important beta-lactamase inhibitor clavulanic acid involves condensation of two primary metabolites, D-glyceraldehyde 3-phosphate and L-arginine, to give N2-(2-carboxyethyl)arginine, a beta-amino acid. This unusual N-C bond forming reaction is catalyzed by the thiamin diphosphate (ThP2)-dependent enzyme N2-(2-carboxyethyl)arginine synthase. Here we report the crystal structure of N2-(2-carboxyethyl)arginine synthase, complexed with ThP2 and Mg2+, to 2.35-A resolution. The structure was solved in two space groups, P2(1)2(1)2(1) and P2(1)2(1)2. In both, the enzyme is observed in a tetrameric form, composed of a dimer of two more tightly associated dimers, consistent with both mass spectrometric and gel filtration chromatography studies. Both ThP2 and Mg2+ cofactors are present at the active site, with ThP2 in a "V" conformation as in related enzymes. A sulfate anion is observed in the active site of the enzyme in a location proposed as a binding site for the phosphate group of the d-glyceraldehyde 3-phosphate substrate. The mechanistic implications of the active site arrangement are discussed, including the potential role of the aminopyrimidine ring of the ThP2. The structure will form a basis for future mechanistic and structural studies, as well as engineering aimed at production of alternative beta-amino acids. Crystal structure and mechanistic implications of N2-(2-carboxyethyl)arginine synthase, the first enzyme in the clavulanic acid biosynthesis pathway.,Caines ME, Elkins JM, Hewitson KS, Schofield CJ J Biol Chem. 2004 Feb 13;279(7):5685-92. Epub 2003 Nov 17. PMID:14623876[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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