Relationships between glycollate and folate metabolism in Euglena gracilis

When division synchronized cultures of Euglena gracilis Klebs (strain Z) were aerated with 5% CO₂ in air the specific activity of glycollate dehydrogenase was only 13% of that in cultures receiving unsupplemented air. The concentrations of 10-formyltetrahydrofolate synthetase (EC 6.3.4.3) and formylfolate derivatives were also lowered by this treatment. In contrast, the specific activity of serine hydroxymethyltransferase (EC 2.1.2.1) and the concentration of methylfolates were raised by supplying CO₂-supplemented air. These effects on enzyme levels were reversed when air was supplied following a period of CO₂ treatment. The levels of glycollate dehydrogenase, 10-formyl-tetrahydrofolate synthetase and formylfolate derivatives were decreased when cells were aerated in media containing 5 mM α-hydroxy-2-pyridinemethane sulphonate. Cell free extracts had the ability to decarboxylate glyoxylate, producing ca equal amounts of CO₂ and formate from C-1 and C-2 respectively. Cells receiving 5% CO₂ in air had a decreased ability to incorporate formate-[¹⁴C] into serine and methionine. It is concluded that during growth at low CO₂ concentrations glycollate metabolism will provide substrate for the formyltetrahydrofolate synthetase reaction.     

One-carbon metabolism in synchronized cultures of Euglena gracilis

The levels of folate derivatives in division synchronized cultures of Euglena gracilis Klebs (strain Z) increased rapidly on a per cell basis durin