Evidence for the allosteric regulation of glycogen synthesis in the intact Escherichia coli cell. Agreement of the values of the parameters of the Hill equation fitted to data for glycogen synthesis in vivo with the abailable values obtained in vitro with adenosine diphosphoglucose synthetase.

In various nutrient-limited cultures of either Escherichia coli W4597(K) or G34 a 10-fold range of rates of glycogen synthesis is observed while the energy charge values (0.86 plus or minus 0.01) and glucose 6-phosphate levels are essentially the same in each condition. The steady state level of fructose 1,6-diphosphate in these cultures varies from experiment to experiment as a function of the observed rate of glycogen synthesis. These data were fitted to the Hill equation by a nonlinear regression analysis and the statistically most probable values obtained for the Hill coefficient (n), A0.5, and V were, respectively, 2.08, 0.82mM, and 1030 mumol/g of protein per hour. The values of the first two parameters agree well with values available at energy charge 0.85 for the in vitro synthesis of ADPG by the ADPG synthetase of E. coli. When the difference in the glucose 1-phosphate concentration used in the studies in vitro from the apparent glucose 1-phosphate concentration in vivo (estimated from the glucose 6-phosphate levels) is considered, the in vitro value of V (1140 mumol of ADPG synthesized per g of protein per hour) is quite similar to the value of V (1030 mumol of glucose incorporated into glycogen per g of protein per hour) for glycogen synthesis in vivo. The close agreement of the values of the parameters of the Hill equation for glycogen synthesis in vivo to the values obtained for ADPG synthesis in vitro provides the most quantitative evidence yet obtained that allosteric regulation of bacterial glycogen synthesis functions in vivo.