5-Enolpyruvylshikimate 3-Phosphate Synthase, the Target Enzyme of the Herbicide Glyphosate, Is Synthesized as a Precursor in a Higher Plant

Abstract
Cell cultures of Corydalis sempervirens adapted to growth in the presence of 5 millimolar glyphosate overproduce the herbicide''s target enzyme, 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase, 30- to 40-fold. In vitro translation of total RNA and poly(A)-RNA coupled with immunoprecipitation showed that the protein is synthesized as a precursor of relative molecular weight (Mr) 53,900 .+-. 900 as compared to Mr 45,500 .+-. 1000 of the mature enzyme. Translatable activity of mRNA for EPSP-synthase in glyphosphate-adapted cultures is tenfold higher than in nonadapted cultures.
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