COORDINATED REGULATION OF AMINO SUGAR-SYNTHESIZING AND SUGAR-DEGRADING ENZYMES IN ESCHERICHIA-COLI K-12

The intracellular concentration of the enzyme glucosamine-6-phosphate synthase, encoded by the gene glmS in Escherichia coli, is repressed a bout threefold by growth on the amino sugars glucosamine and N-acetylg lucosamine. This regulation occurs at the level of glmS transcription. It is not due just to the presence of intracellular amino sugar phosp hates, because mutations which derepress the genes of the nag regulon (coding for proteins involved in the uptake and metabolism of N-acetyl glucosamine) also repress the expression of glmS in the absence of exo genous amino sugars.