Crystal Structure of the Bifunctional Chorismate Synthase from Saccharomyces cerevisiae

• Published in: The Journal of biological chemistry 2004-01, Vol.279 (1), p.619-625
• Main Authors: Quevillon-Cheruel, Sophie, Leulliot, Nicolas, Meyer, Philippe, Graille, Marc, Bremang, Michael, Blondeau, Karine, Sorel, Isabelle, Poupon, Anne, Janin, Joël, van Tilbeurgh, Herman
• Format: Article
• Language: English
• Subjects: 5-enolpyruvylshikimate 3-phosphate; Amino Acid Sequence; chorismate; Cloning, Molecular; Crystallography, X-Ray; FMN; Life Sciences; Models, Molecular; Molecular Sequence Data; Phosphorus-Oxygen Lyases - chemistry; Phosphorus-Oxygen Lyases - metabolism; Protein Conformation; Protein Folding; Protein Structure, Secondary; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Sensitivity and Specificity; Sequence Alignment; Sequence Homology, Amino Acid
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M310380200

Chorismate synthase (EC 4.2.3.5), the seventh enzyme in the shikimate pathway, catalyzes the transformation of 5-enolpyruvylshikimate 3-phosphate (EPSP) to chorismate, which is the last common precursor in the biosynthesis of numerous aromatic compounds in bacteria, fungi, and plants. The chorismate synthase reaction involves a 1,4-trans-elimination of phosphoric acid from EPSP and has an absolute requirement for reduced FMN as a cofactor. We have determined the three-dimensional x-ray structure of the yeast chorismate synthase from selenomethionine-labeled crystals at 2.2-Å resolution. The structure shows a novel βαβα fold consisting of an alternate tight packing of two α-helical and two β-sheet layers, showing no resemblance to any documented protein structure. The molecule is arranged as a tight tetramer with D2 symmetry, in accordance with its quaternary structure in solution. Electron density is missing for 23% of the amino acids, spread over sequence regions that in the three-dimensional structure converge on the surface of the protein. Many totally conserved residues are contained within these regions, and they probably form a structured but mobile domain that closes over a cleft upon substrate binding and catalysis. This hypothesis is supported by previously published spectroscopic measurements implying that the enzyme undergoes considerable structural changes upon binding of both FMN and EPSP.