Location of the active site of allosteric chorismate mutase from Saccharomyces cerevisiae, and comments on the catalytic and regulatory mechanisms.

AUTOR(ES)

Xue, Y

RESUMO

The active site of the allosteric chorismate mutase (chorismate pyruvatemutase, EC 5.4.99.5) from yeast Saccharomyces cerevisiae (YCM) was located by comparison with the mutase domain (ECM) of chorismate mutase/prephenate dehydratase [prephenate hydro-lyase (decarboxylating), EC 4.2.1.51] (the P protein) from Escherichia coli. Active site domains of these two enzymes show very similar four-helix bundles, each of 94 residues which superimpose with a rms deviation of 1.06 A. Of the seven active site residues, four are conserved: the two arginines, which bind to the inhibitor's two carboxylates; the lysine, which binds to the ether oxygen; and the glutamate, which binds to the inhibitor's hydroxyl group in ECM and presumably in YCM. The other three residues in YCM (ECM) are Thr-242 (Ser-84), Asn-194 (Asp-48), and Glu-246 (Gln-88). This Glu-246, modeled close to the ether oxygen of chorismate in YCM, may function as a polarizing or ionizable group, which provides another facet to the catalytic mechanism.

Documentos Relacionados

• Substrate conformational transitions in the active site of chorismate mutase: Their role in the catalytic mechanism
• Refined molecular hinge between allosteric and catalytic domain determines allosteric regulation and stability of fungal chorismate mutase
• Allosteric Regulation of Catalytic Activity: Escherichia coli Aspartate Transcarbamoylase versus Yeast Chorismate Mutase
• Yeast chorismate mutase in the R state: Simulations of the active site
• Separation of inhibition and activation of the allosteric yeast chorismate mutase