Effect of chloramphenicol on the development of proplastids in Euglena gracilis: I. The synthesis of ribulosediphosphate carboxylase, NADP-linked glyceraldehyde-3-phosphate dehydrogenase and aminolaevulinate dehydratase

Abstract

Summary In a crude homogenate of dark-grown Euglena ribulose-diphosphate carboxylase, NADP-linked glyceraldehyde-3-phosphate dehydrogenase and aminolaevulinate dehydratase activities are found. These enzymes are localized exclusively or (as for aminolaevulinate dehydratase) partly in the proplastids. If the cells are being cultivated for a number of generations in the dark in the presence of chloramphenicol, then the synthesis of ribulosediphosphate carboxylase and NADP-linked glyceraldehyde-3-phosphate dehydrogenase is inhibited, but that of aminolaevulinate dehydratase is not changed. The results signify that in the dark proteins are synthesized on the ribosomes of the proplastids. The synthesis of ribulosediphosphate carboxylase and NADP-linked gly-ceraldehyde-3-phosphate dehydrogenase is dependent on the protein synthesis in the proplastid. The aminolaevulinate dehydratase in the proplastid is probably synthesized in the cytoplasm and subsequently incorporated in the proplastid. The proplastid appears to be equivalent to the chloroplast in relation to the synthesis of these enzymes.