The nature of the energy metabolite responsible for sugar accumulation in Chlorella vulgaris

Summary 2-Deoxyglucose is taken up by Chlorella vulgaris via the inducible non-phosphorylating hexose transport system. Since this hexose analogue is phosphorylated to a minor extent within the cells by hexokinase, the rate of uptake can be compared with the rate of an ATP dependent phosphorylation. The effect of the transphosphorylation inhibitors azide, DCCD, and oligomycin on these two processes has been investigated. The data especially with azide and DCCD clearly show that the ATP-dependent phosphorylation is much more severely inhibited than the rate of uptake. This was observed under aerobic conditions in the dark, as well as under anaerobic conditions in the light. Under anaerobiosis in the dark however there was no difference in the degree of inhibition. The same was true under all conditions with FCCP. These results are interpreted as evidence that a high energy intermediate of oxidative or photosynthetic phosphorylation drives the active sugar uptake of Chlorella. Under anaerobic conditions in the dark this high energy intermediate may be produced via ATP.