Effect of sugars on early biochemical events in development of Dictyostelium discoideum

Metabolizable sugars blocked development of the slime mold Dictyostelium discoideum; the same sugars also inhibited the formation of contact sites "A", of membranal 3':5'-cyclic adenosine monophosphate (cAMP)-binding sites, and of total cAMP phosphodoesterase (3':5'-cyclic-nucleotide phosphodiesterase; EC 3.1.4.17; 3':5'-cyclic-nucleotide 5'-nucleotidohydrolase). These inhibitory effects of the sugars on the synthesis of cellular components, required for the aggregation of developing amebae, were paralleled by an inhibition of the accumulation of cAMP which normally accompanies development. The inhibition by sugars could be overcome partially by pulsing the amebae with nanomolar concentrations of cAMP only after the amebae had acquired cAMP-binding sites. The findings suggest that metabolizable sugars inhibit development by blocking the formation of cAMP and, conversely, that development in D. discoideum may be related to the energetic state of the cell.