Transcription and translation for carotenoid synthesis inChlamydomonas reinhardtii

摘要

The sites of transcription and translation of carotenoid pigments were studied in synchronously grown cells ofChlamydomonas reinhardtiiDang. Rifampicin, cycloheximide and spectinomycin were used to distinguish between the nuclear-cytoplasmic genetic system and the genetic system of the chloroplast. Since rifampicin is without effect, chloroplast DNA appears not to possess information required for the synthesis of carotenoids. Carotenoid synthesis parallels chlorophyll synthesis in these cells. Carotenoid synthesis is dependent onde novoprotein synthesis both on cytoplasmic and chloroplast ribosomes, for both cycloheximide and spectinomycin are effective inhibitors. However, the cells are able to form about 40 of the expected increase in carotenoids when cytoplasmic and chloroplast ribosomes are simultaneously inhibited. Of the major carotenoids inC. reinhardtii, lutein appears the least dependent onde novoprotein synthesis. The synthesis of β-carotene and trollein appears to be completely dependent on the function of cytoplasmic ribosomes