Synthesis of photosynthetic membrane proteins directed by RNA from rough thylakoids of Chlamydomonas reinhardtii.

Messenger RNA activities associated with thylakoids of Chlamydomonas reinhardtii were examined by translation of RNA of rough thylakoids (thylakoids with bound ribosomes) in a wheat germ protein-synthesis system. The RNA fraction, active in translation, did not bind to oligod (T)-cellulose indicating that the mRNA associated with the rough thylakoids contains little, if any, 3' polyadenylic acid. Assuming that 1% of the thylakoid RNA was mRNA, it was found to have a specific translation activity between that of globin mRNA and tobacco mosaic virus RNA. Translation products of thylakoid RNA were immunoprecipitated by crossed immunoelectrophoresis, using antisera to two polypeptides synthesized within the chloroplast, one of which specifically precipitates the beta subunit of chloroplast coupling factor 1. Each antiserum immunoprecipitated radioactive polypeptide from translates of thylakoid RNA, indicating that the presence of mRNA for both polypeptides is associated with the thylakoids. The results suggest that thylakoid-bound polyribosomes are involved in the synthesis of thylakoid polypeptides.