Blue light-induced formation of phosphoenolpyruvate carboxylase in colorless <italic>Chlorella</italic> mutant cells

Abstract

The activities of NAD-malic dehydrogenase, aspartate aminotransferase, phosphoenolpyruvate carboxylase and NADP-malic enzyme in colorless mutant cells of Chlorella vulgaris (Mutant No. 125) decreased during starvation (in phosphate buffer in darkness). The most pronounced decrease was observed in phosphoenolpyruvate carboxylase activity. A trace of ribulose diphosphate carboxylase activity detected in the growing cells disappeared on starvation and no activity of pyruvate carboxylase was detected in these mutant cells. Blue light (462 or 465 nm) enhanced phosphoenolpyruvate carboxylase activity in the starved cells about 2-fold, while the activities of aspartate aminotransferase and NADP-malic enzyme were slightly lowered by the blue light. Red light (mainly 600–650 nm) brought about a slight decrease in all the enzyme activities tested. Cycloheximide (5 μ/ml) completely abolished the enhancing effect of blue light on phosphoenolpyruvate carboxylase activity, indicating that the short wavelength light specifically increased the de novo synthesis of this enzyme.