5-enolpyruvyl shikimate 3-phosphate synthase

This enzyme [EC 2.5.1.19], also known as 5-enolpyruvyl-shikimate-3-phosphate synthase and 3-enolpyruvoyl-shikimate-5-phosphate synthase, catalyzes the reaction of phosphoenolpyruvate with 3-phosphoshikimate to produce orthophosphate and 5-0-(l-carboxyvinyl)-3-phosphoshikimate. 

Aromatic Amino Acid Biosynthesis. The shikimate pathway is the biosynthetic route to the aromatic amino acids tryptophan, tyrosine and phenylalanine as well as a large number of secondary metabolites such as flavonoids, anthocyanins, auxins and alkaloids. One enzyme in this pathway is 5-enolpyruvyl shikimate-3-phosphate synthase (EPSP synthase) (Figure 2.9). 

The mode of action is by inhibiting 5-enolpyruvyl-shikimate-3-phosphate synthase. Roundup shuts down the production of the aromatic amino acids phenylalanine, tyrosine, and tryptophane (30). Whereas all these amino acids are essential to the survival of the plant, tryptophane is especially important because it is the progenitor for indole-3-acetic acid, or auxin, which plays an important role in growth and development, and controls cell extension and organogenesis. 

Inhibits 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS), an enzyme of the aromatic acid and biosynthesis pathway. This prevents synthesis of essential aromatic amino acids needed for protein biosynthesis... 

It is now well established that the primary metabolic target of glyphosate is an enzyme of the shikimic acid metabolic pathway, enolpyruvyl shikimate-3-phosphate synthase (2.f ). Via this action, glyphosate blocks the synthesis of the end products of this pathway, notably phenylalanine and tryptophan, but also various subsequent products (Figure 1) ( ,i). It has seemed logical to conclude that the herbicidal effect of glyphosate is a direct result of its effect on the shikimic acid pathway. 

RR soybean was developed using a glyphosate insensitive CP4-EPSPS (5-enolpyruvyl shikimate 3-phosphate synthase). Since its introduction in 1996, RR soybean has increased steadily from 2 to 89% of the total soybean acres grown in 2005 (Fig. 6.1.2). The widespread adoption of RR soybeans has resulted in significant grower and environmental benefits. In 2004 alone, RR soybeans reduced grower production costs by 1.37 billion and pesticide use by 22.4 million pounds. Furthermore, there has been about a 64% increase in the number of no-till soybean acres that decreased soil erosion, dust and pesticide run-off, and improved soil moisture, air and water quality [2]. 

Mechanism of enolpyruvyl shikimate 3-phosphate synthase exchange of phosphoenolpyruvate with solvent protons. Biochemistry 22 5903-5908. 

STEINRUCKEN, H.C., N. AMRHEIN. 1980. The herbicide glyphosate is a potent inhibitor of 5-enolpyruvyl-shikimic acid 3-phosphate synthase. Biochem. Biophys. Res. Commun. 94 1207-1212. 

A number of analogues that mimic the intermediate formed during the EPSP nthase conversion of shikimic-3-phosphate into EPSP (5-enolpyruvyl shikimate-3-phosphate) have been prepared and tested as inhibitors of the enzyme. The best was shown to be 63. (Z)-3-Fluoro-phosphoenolpyruvate functions as a pseudosubstrate for EPSP synthase producing in one step the same adduct 63, but as an isomeric mixture. ... 

EPSP synthase catalyzes a rare type of reaction in which the intact enolpyruvyl (carboxyvinyl) group is transferred from phosphoenolpyruvate (PEP) to the 5-hydroxyl group of shikimate 3-phosphate (Fig. 6). This type of reaction is encountered in only one other known enz3rmatic process the transfer of the enolpyruvyl group to UDP-N-... 

Enolpyruvylshikimate-3-phosphate (EPSP) synthase (EC 2.5.1.19), also known as 3-phosphoshikimate 1-carboxyvinyltransferase, catalyzes the reversible transfer of the enolpyruvyl group from PEP to shikimate 3-phosphate (Figure 2.2). There is no known cofactor requirement. When purified to homogeneity, bacterial and plant EPSP synthases are monomeric monofunctional proteins of molecular weight 40,000-50,000. " Some fungi have a radically different molecular architecture in which EPSP synthase is part of a pentafunctional polypeptide which also contains the previous four enzymatic activities of the common shikimate pathway, the arom complex. 

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