The Shikimate Pathway

Abstract

The shikimate pathway links metabolism of carbohydrates to biosynthesis of aromatic compounds. In a sequence of seven metabolic steps, phosphoenolpyruvate and erythrose 4-phosphate are converted to chorismate, the precursor of the aromatic amino acids and many aromatic secondary metabolites. All pathway intermediates can also be considered branch point compounds that may serve as substrates for other metabolic pathways. The shikimate pathway is found only in microorganisms and plants, never in animals. All enzymes of this pathway have been obtained in pure form from prokaryotic and eukaryotic sources and their respective DNAs have been characterized from several organisms. The cDNAs of higher plants encode proteins with amino terminal signal sequences for plastid import, suggesting that plastids are the exclusive locale for chorismate biosynthesis. In microorganisms, the shikimate pathway is regulated by feedback inhibition and by repression of the first enzyme. In higher plants, no physiological feedback inhibitor has been identified, suggesting that pathway regulation may occur exclusively at the genetic level. This difference between microorganisms and plants is reflected in the unusually large variation in the primary structures of the respective first enzymes. Several of the pathway enzymes occur in isoenzymic forms whose expression varies with changing environmental conditions and, within the plant, from organ to organ. The penultimate enzyme of the pathway is the sole target for the herbicide glyphosate. Glyphosate-tolerant transgenic plants are at the core of novel weed control systems for several crop plants.

The use of biodiversity as source of new chemical entities against defined molecular targets for treatment of malaria, tuberculosis, and T-cell mediated diseases: a review

“…4;Bentley 1990, Herrmann & Weaver 1999, Coggins et al 2003. The shikimate pathway links metabolism of carbohydrates to biosynthesis of aromatic compounds.…”

“…4: the mycobacterial shikimate pathway (the main trunk) leads to the biosynthesis of chorismic acid, which is converted by five distinct enzymes to prephenate (precursor of phenylalanine and tyrosine), anthranilate (precursor of tryptophan), aminodeoxychorismate (precursor of para-aminobenzoic acid -PABA -which, in turn, leads to tetrahydrofolate synthesis), para-hydroxybenzoic acid (precursor of ubiquinone or Coenzyme Q), and isochorismate (common precursor of naphthoquinones, menaquinones and mycobactins) (Fig. 5;Herrmann & Weaver 1999). Analysis of the complete genome sequence of Mycobacterium tuberculosis shows the presence of seven aro genes predicted to be involved in the shikimate pathway (Cole et al 1998).…”

Elevated production of the aromatic fragrance molecule, 2‐phenylethanol, using Metschnikowia pulcherrima through both de novo and ex novo conversion in batch and continuous modes

“…This pathway also includes the biosynthesis of alternative higher alcohols with aromatic amino acids as precursors. Another pathway, the Shikimate pathway, governs the de novo synthesis of L‐phenylalanine when L‐phenylalanine in the media is scarce, producing aromatic amino acids from glucose via D‐erythrose‐4‐phosphate 5, 6. The Shikimate pathway therefore links the metabolism between carbohydrate and amino acid production in several organisms, particularly plants and microorganisms 5.…”

“…Another pathway, the Shikimate pathway, governs the de novo synthesis of L‐phenylalanine when L‐phenylalanine in the media is scarce, producing aromatic amino acids from glucose via D‐erythrose‐4‐phosphate 5, 6. The Shikimate pathway therefore links the metabolism between carbohydrate and amino acid production in several organisms, particularly plants and microorganisms 5. Essential aromatic amino acids, such as L‐phenylalanine, L‐tyrosine and L‐tryptophan are created via this pathway, mostly for the synthesis of polypeptides.…”

Citotoxicidad del glifosato en células mononucleares de sangre periférica humana

“…Su acción herbicida se debe a la inhibición de la síntesis de aminoácidos aromá-ticos en plantas y microorganismos (2,3) por inactivación de la enzima 5-enolpiruvil-chiquimato-3-fosfato sintetasa (4,5). Debido a que esta vía es específica para plantas y microorganismos, el mecanismo no es considerado de riesgo para humanos y en el año 2000 un articulo de revisión concluyó que el herbicida Roundup® no constituía un riesgo para la salud humana (1).…”