|EPSP Synthase (3-phosphoshikimate 1-carboxyvinyltransferase)|
EPSP synthase liganded with shikimate.
|PDB structures||RCSB PDB PDBe PDBsum|
|Gene Ontology||AmiGO / QuickGO|
|EPSP synthase (3-phosphoshikimate 1-carboxyvinyltransferase)|
Ribbon diagram of EPSP synthase
- phosphoenolpyruvate + 3-phosphoshikimate ⇌ phosphate + 5-enolpyruvylshikimate-3-phosphate (EPSP)
The enzyme belongs to the family of transferases, to be specific those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is phosphoenolpyruvate:3-phosphoshikimate 5-O-(1-carboxyvinyl)-transferase. Other names in common use include:
- 5-enolpyruvylshikimate-3-phosphate synthase,
- 3-enolpyruvylshikimate 5-phosphate synthase,
- 3-enolpyruvylshikimic acid-5-phosphate synthetase,
- 5'-enolpyruvylshikimate-3-phosphate synthase,
- 5-enolpyruvyl-3-phosphoshikimate synthase,
- 5-enolpyruvylshikimate-3-phosphate synthetase,
- 5-enolpyruvylshikimate-3-phosphoric acid synthase,
- enolpyruvylshikimate phosphate synthase, and
- 3-phosphoshikimate 1-carboxyvinyl transferase.
EPSP synthase is a monomeric enzyme with a molecular mass of about 46,000. It is composed of two domains, which are joined by protein strands. This strand acts as a hinge, and can bring the two protein domains closer together. When a substrate binds to the enzyme, ligand bonding causes the two parts of the enzyme to clamp down around the substrate in the active site.
EPSP synthase has been divided into two groups according to glyphosate sensitivity. Class I enzyme, contained in plants and in some bacteria, is inhibited at low micromolar glyphosate concentrations, whereas class II enzyme, found in other bacteria, is resistant to inhibition by glyphosate.
EPSP synthase participates in the biosynthesis of the aromatic amino acids phenylalanine, tyrosine and tryptophan via the shikimate pathway in bacteria, fungi, and plants. EPSP synthase is produced only by plants and micro-organisms; the gene coding for it is not in the mammalian genome. Gut flora of some animals contain EPSPS.
EPSP synthase catalyzes the reaction which converts shikimate-3-phosphate plus phosphoenolpyruvate to 5-enolpyruvylshikimate-3-phosphate (EPSP).
EPSP synthase is the biological target for the herbicide glyphosate. Glyphosate is a competitive inhibitor of PEP, acting as a transition state analog that binds more tightly to the EPSPS-S3P complex than PEP and inhibits the shikimate pathway. This binding leads to inhibition of the enzyme's catalysis and shuts down the pathway. Eventually this results in organism death from lack of aromatic amino acids the organism requires to survive.
A version of the enzyme that both was resistant to glyphosate and that was still efficient enough to drive adequate plant growth was identified by Monsanto scientists after much trial and error in an Agrobacterium strain called CP4, which was found surviving in a waste-fed column at a glyphosate production facility; this version of enzyme, CP4 EPSPS, is the one that has been engineered into several genetically modified crops.
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- Goldsbrough, Peter (1990). "Goldsbrough, Peter B., et al. "Gene amplification in glyphosate tolerant tobacco cells." Plant science 72.1 (1990): 53-62". Plant Science. 72 (1): 53–62. doi:10.1016/0168-9452(90)90186-r.
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- Ream JE, Steinrücken HC, Porter CA, Sikorski JA (May 1988). "Purification and Properties of 5-Enolpyruvylshikimate-3-Phosphate Synthase from Dark-Grown Seedlings of Sorghum bicolor". Plant Physiology. 87 (1): 232–8. doi:10.1104/pp.87.1.232. PMC . PMID 16666109.
- Pollegioni L, Schonbrunn E, Siehl D (Aug 2011). "Molecular basis of glyphosate resistance-different approaches through protein engineering". The FEBS Journal. 278 (16): 2753–66. doi:10.1111/j.1742-4658.2011.08214.x. PMC . PMID 21668647.
- Funke T, Han H, Healy-Fried ML, Fischer M, Schönbrunn E (Aug 2006). "Molecular basis for the herbicide resistance of Roundup Ready crops". Proceedings of the National Academy of Sciences of the United States of America. 103 (35): 13010–5. Bibcode:2006PNAS..10313010F. doi:10.1073/pnas.0603638103. JSTOR 30050705. PMC . PMID 16916934.
- Maeda H, Dudareva N (2012). "The shikimate pathway and aromatic amino Acid biosynthesis in plants". Annual Review of Plant Biology. 63 (1): 73–105. doi:10.1146/annurev-arplant-042811-105439. PMID 22554242.
The AAA pathways consist of the shikimate pathway (the prechorismate pathway) and individual postchorismate pathways leading to Trp, Phe, and Tyr.... These pathways are found in bacteria, fungi, plants, and some protists but are absent in animals. Therefore, AAAs and some of their derivatives (vitamins) are essential nutrients in the human diet, although in animals Tyr can be synthesized from Phe by Phe hydroxylase....The absence of the AAA pathways in animals also makes these pathways attractive targets for antimicrobial agents and herbicides.
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- Jaworski EK (1972). "Mode of action of N-phosphonomethyl-glycine: inhibition of aromatic amino acid biosynthesis". J Agric Food Chem. 20: 1195–1198. doi:10.1021/jf60184a057.
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- Green JM, Owen MD (Jun 2011). "Herbicide-resistant crops: utilities and limitations for herbicide-resistant weed management". Journal of Agricultural and Food Chemistry. 59 (11): 5819–29. doi:10.1021/jf101286h. PMC . PMID 20586458.
- Morell H, Clark MJ, Knowles PF, Sprinson DB (Jan 1967). "The enzymic synthesis of chorismic and prephenic acids from 3-enolpyruvylshikimic acid 5-phosphate". The Journal of Biological Chemistry. 242 (1): 82–90. PMID 4289188.