[Mechanism of action of glucose on L-asparaginase synthesis by Escherichia coli bacteria]

Abstract

The synthesis of L-asparaginase in Escherichia coli W and E. coli K-12 was almost completely supressed if glucose was added at a concentration of 0.5 per cent to a growth medium. The level of L-asparaginase synthesis decreased by ca. 75 per cent as a result of cyamutations when the bacteria could not produce cyclo-3',5'-AMP (cAMP). Apparently, a decrease in the intracellular content of cAMP caused by glucose could not be the only factor inhibiting L-asparaginase synthesis. Lactate was found to stimulate L-asparaginase synthesis. Glucose caused the catabolite repression and catabolite inhibition of the components of a system involved in lactate transport. The inhibition of L-asparaginase synthesis by glucose seems to be due, at least partly, to the fact that it prevents the assimilation of lactate by the cells, as well as the utilization of some other compounds which stimulate synthesis of this enzyme.