Differential sensitivity of bacterial 5-enolpyruvylshikimate-3-phosphate synthases to the herbicide glyphosate

The potent inhibition of the shikimate pathway enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase by the broad-spectrum herbicide glyphosate (N-[phosphonomethyl]glycine) was confirmed for the enzymes extracted from various bacteria, a green alga and higher plants. However, 5 out of 6 species belonging to the genus Pseudomonas were found to have EPSP synthases with a 50- to 100-fold decreased sensitivity to the inhibitor. Correspondingly, growth of these 5 species was not inhibited by 5 mM glyphosate, and the organisms did not excrete shikimate-3-phosphate in the presence of the herbicide.