[The mechanism of action of the herbicide N-(phosphonomethyl)glycine: its effect on the growth and the enzymes of aromatic amino acid biosynthesis in Escherichia coli (author's transl)]

Abstract

N-(Phosphonomethyl) glycine prolongates the lag-phase and inhibits the growth rate of Escherichia coli, Salmonella typhimurium and Pseudomonas aureofaciens. The eucaryotes Saccharomyces cerevisiae and Neurospora crassa are not inhibited. The effect of growth inhibition in an E. coli culture depends on the time of the herbicide addition and no cells showing resistance against it are observed. The inhibitory effect can be overcome completely by a mixture of phenylalanine, tyrosine and tryptophan. N-(Phosphonomethyl)glycine inhibits phospho-2-oxo-3-deoxyheptonate aldolase and 3-dehydroquinate synthase. Both inhibitory effects are removed by addition of CO2. Chorismate mutase, prephenate dehydratase and prephenate dehydrogenase are not influenced by this herbicide. Anthranilate synthase is also inhibited by N-(phosphonomethyl)glycine. This inhibition is removed by addition of Mg2. Phospho-2-oxo-3-deoxyheptonate aldoase is derepressed in E. coli cells grown in minimal medium containing N-(phosphonomethyl)glycine. Under these conditions the tyrosine-sensitive isoenyme is much more strongly derepressed than the phenylalanine-sensitive isoenzyme. 3-Dehydroquinate synthase is not affected. Chorismate mutase, prephenate dehydrogenase, prephenate dehydratase, and anthranilate synthase are derepressed, but to a lesser extent.