1fnk

CRYSTAL STRUCTURE ANALYSIS OF CHORISMATE MUTASE MUTANT C88K/R90S

spinqualitylabelsall models 1fnk, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1fnk is a 1 chain structure with sequence from Bacillus subtilis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: CSD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AROH_BACSU Catalyzes the Claisen rearrangement of chorismate to prephenate. Probably involved in the aromatic amino acid biosynthesis. 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 PubMed Combinatorial mutagenesis and in vivo selection experiments previously afforded functional variants of the AroH class Bacillus subtilis chorismate mutase lacking the otherwise highly conserved active site residue Arg(90). Here, we present a detailed kinetic and crystallographic study of several such variants. Removing the arginine side chain (R90G and R90A) reduced catalytic efficiency by more than 5 orders of magnitude. Reintroducing a positive charge to the active site through lysine substitutions restored more than a factor of a thousand in k(cat). Remarkably, the lysine could be placed at position 90 or at the more remote position 88 provided a sterically suitable residue was present at the partner site. Crystal structures of the double mutants C88S/R90K and C88K/R90S show that the lysine adopts an extended conformation that would place its epsilon-ammonium group within hydrogen-bonding distance of the ether oxygen of bound chorismate in the transition state. These results provide support for the hypothesis that developing negative charge in the highly polarized transition state is stabilized electrostatically by a strategically placed cation. The implications of this finding for the mechanism of all natural chorismate mutases and for the design of artificial catalysts are discussed. A strategically positioned cation is crucial for efficient catalysis by chorismate mutase.,Kast P, Grisostomi C, Chen IA, Li S, Krengel U, Xue Y, Hilvert D J Biol Chem. 2000 Nov 24;275(47):36832-8. PMID:10960481 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also 3D structures of chorismate mutase

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