Control of amino sugar metabolism in Escherichia coli and isolation of mutants unable to degrade amino sugars

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Abstract
The growth of E. coli on glucosamine results in an induction of glucosamine 6-phosphate deaminase [2-amino-2-deoxy-D-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] and a repression of glucosamine 6-phosphate synthetase (L-glutamine-D-fructose 6-phosphate aminotransferase, EC 2.6.1.16); glucose abolishes these control effects. Growth of E. coli on N -acetylglucosamine results in an induction of N-acetylglucosamine 6-phosphate deacetylase and glucosamine 8-phosphate deaminase, and in a repression of glucosamine 6-phosphate synthetase; glucose diminishes these control effects. The synthesis of amino sugar kinases (EC 2.7.1.8 and 2.7.1.9) is unaffected by growth on amino sugars. Glucosamine 6-phosphate synthetase is inhibited by glucosamine 6-phosphate. Mutants of E. coli that are unable to grow on N-acetylglucosamine which were isolated lack either N-acetylglucosamine 6-phosphate deacetylase (deacetylaseless) or glucosamine 6-phosphate deaminase (deaminase-less). Deacetylaseless mutants can grow on glucosamine but deaminase-less mutants cannot. After growth on glucose, deacetylaseless mutants have a repressed glucosamine 6-phosphate synthetase and a superinduced glucosamine 6-phosphate deaminase; this may be related to an intracellulax accumulation of acetylamino sugar that also occurs under these conditions. In 1 mutant the acetylamino sugar was shown to be partly N-acetylglucosamine 6-phosphate. Deaminaseless mutants have no abnormal control effects after growth on glucose. Addition of N-acetylglucosamine or glucosamine to cultures of a deaminaseless mutant inhibited growth. Addition of N-acetylglucosamine to cultures of a deacetylaseless mutant caused lysis, and secondary mutants were isolated that did not lyse; most of these secondary mutants had lost glucosamine 6-phosphate deaminase and an uptake mechanism for N-acetylglucosamine. Similar amounts of C14 were incorporated from [l-Cl4]-glucosamine by cells of mutants and wild-type growing on broth. Cells of wild-type and a deaminaseless mutant incorporated C14 from N-acetyl[C14]glucosamine more efficiently than from N[l-Cl4] acetylglucosamine, incorporation from the latter being further decreased by acetate; cells of a deacetylaseless mutant showed a poor incorporation of both types of labelled N-acetylglucosamine.