Mode of action of glyphosate in Candida maltosa.
The broad-spectrum herbicide glyphosate inhibits the growth of Candida maltosa and causes the accumulation of shikimic acid and shikimate-3-phosphate. Glyphosate is a potent inhibitor of three enzymes of aromatic amino acid biosynthesis in this yeast. In relation to tyrosine-sensitive 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase and dehydroquinate synthase, the inhibitory effect appears at concentrations in the mM range, but 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase is inhibited by micromolar concentrations of glyphosate. Inhibition of partially purified EPSP synthase reaction by glyphosate is competitive with respect to phosphoenolpyruvate (PEP) with a Ki-value of 12 microM. The app. Km for PEP is about 5-fold higher and was 62 microM. Furthermore, the presence of glyphosate leads to derepression of many amino acid biosynthetic enzymes.
D010723:3-Deoxy-7-Phosphoheptulonate Synthase / Q000378:metabolism; D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D019883:Alkyl and Aryl Transferases; D002175:Candida / Q000187:drug effects* / Q000378:metabolism; D002474:Cell-Free System; D004794:Enzyme Repression; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology*; D008190:Lyases / Q000378:metabolism; D019761:Phosphorus-Oxygen Lyases; D012765:Shikimic Acid / Q000096:biosynthesis; D014166:Transferases / Q000378:metabolism; D000097797:Glyphosate
D010723:3-Deoxy-7-Phosphoheptulonate Synthase; D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D019883:Alkyl and Aryl Transferases; D005998:Glycine; D006540:Herbicides; D008190:Lyases; D019761:Phosphorus-Oxygen Lyases; D012765:Shikimic Acid; D014166:Transferases; D000097797:Glyphosate; C020001:3-dehydroquinate synthetase