Chorismate biosynthesis (Saccharomyces cerevisiae)

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Chorismate, an intermediate in the synthesis of the aromatic amino acids and the vitamins, p-aminobenzoate and p-hydroxybenzoate, is synthesized by the shikimate pathway. The shikimate pathway has been found to be common to all eukaryotes and prokaryotes studied thus far (as reported in. In Saccharomyces cerevisiae the initial step is catalyzed by two deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase isoenzymes, one of which (ARO3) is feedback inhibited by phenylalanine, and the other (ARO4) by tyrosine. Both DAHP isoenzymes are derepressed by amino acid starvation (general control of amino acid biosynthesis). The 5 subsequent reactions are catalyzed by the pentafunctional arom enzyme, Aro1p. Aro1p is a mosaic of five monofunctional domains, each of which corresponds to one of five separate monofunctional E. coli enzymes. The last step of chorismate biosynthesis, before the pathway branches to synthesize different terminal products, is catalyzed by Aro2p. Description from YeastPathways.