Plant Physiology 56:600-604 (1975)
© 1975 American Society of Plant Biologists
Articles
Ribulose 1,5-Diphosphate Carboxylase Synthesis in Euglena
II. Effect of Inhibitors on Enzyme Synthesis during Regreening and Subsequent Transfer to Darkness
J. Michael Lord,
Terence L. Armitage and
Mi hael J. Merrett
1 Postgraduate School of Studies in Biological Sciences, University of Bradford, Bradford, Yorkshire, BD7 1DP England
Dark-grown Euglena gracilis Klebs strain Z Pringsheim cells, which have been partially regreened in the light, show a striking, continued synthesis of the chloroplast enzyme ribulose 1,5-diphosphate carboxylase on transfer back into darkness. This dark synthesis of the enzyme was completely prevented by the addition of 15 µg/ml of cycloheximide to the culture medium but was unaffected, for at least 8 hours, by the addition of 1 mg/ml of D-threo-chloramphenicol. The addition of either cycloheximide or D-threo-chloramphenicol to dark-grown cultures at the onset of illumination completely inhibited the light-induced synthesis of ribulose 1,5-diphosphate carboxylase. When cells which had been illuminated in the presence of D-threo-chloramphenicol, and hence were unable to synthesize ribulose 1,5-diphosphate carboxylase, were transferred to darkness in the absence of this inhibitor, synthesis of the carboxylase then occurred. Dark-grown cells which had been illuminated in the presence of cycloheximide failed to synthesize the enzyme when placed in the dark in the absence of cycloheximide. The addition of 5-fluorouracil to regreening cultures to prevent light-induced transcriptional steps completely blocked the synthesis of ribulose 1,5-diphosphate carboxylase.
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