Inhibition of the growth of Leuconostoc mesenteroides by the toxic factor from "agenized" zein: reversal by l-glutamine

Effect of methionine sulfoximine and methionine sulfone on glutamate synthesis in Klebsiella aerogenes

At least two pathways exist in Klebsiella aerogenes for glutamate synthesis. A mutant blocked in one pathway due to the loss of glutamate dehydrogenase (gltD) does not require glutamate and has the same growth characteristics as the parent strain in most media; however, its growth is inhibited by the analogues methionine sulfoximine and methionine sulfone. Wild-type Klebsiella is resistant to 0.1 M methionine sulfoximine or methionine sulfone, whereas the gltD mutant is sensitive to 1 mM concentrations. Either glutamate or glutamine is effective in overcoming this inhibition. Activities of both glutamine synthetase and glutamate synthetase, two enzymes involved in the second pathway of glutamate synthesis, are inhibited by methionine sulfoximine and methionine sulfone. The primary effect of methionine sulfoximine appears to be the prevention of glutamine production necessary for subsequent glutamate synthesis via glutamate synthetase enzyme.

Phosphorylation of methionine sulfoximine by glutamine synthetase

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STUDIES ON THE INHIBITION OF GLUTAMIC ACID UTILIZATION IN LACTOBACILLUS PLANTARUM

Eighteen compounds including five novel γ-substituted glutamic acid analogues were tested for inhibition of the utilization of L-glutamic acid by Lactobacillus plantarum. All of the test compounds were found to be less active than DL-methionine sulphoxide, a known glutamic acid antagonist, in inhibiting" the growth of L. plantarum. γ-Methylene-DL-glutamic acid and N-benzyl-α-methyl-DL-pyroglutamic acid were found to be the most active inhibitors of bacterial growth. The inhibition of growth produced by γ-methylene-DL-glutamic acid was readily reversed by L-glutamic acid; whereas the inhibition caused by α-methyl-DL-pyroglutamic acid was more refractory to reversal by L-glutamic acid.