INVITRO SYNTHESIS OF CHLOROPLAST FERREDOXIN AS A HIGH MOLECULAR-WEIGHT PRECURSOR IN A CELL-FREE PROTEIN SYNTHESIZING SYSTEM FROM WHEAT GERMS

RNA isolated from leaves of Nicotiana tabacum, etiolated leaves of Phaseolus vulgaris and from cells of Chlamydomonas reinhardii, can be translated in cell-free extracts derived from wheat germs. The in vitro products were identified by SDS electrophoresis after immunoprecipitation with specific antisera against ferredoxin. The in vitro products appeared to have a Mr 20,500, in contrast to authentic ferredoxin that has a Mr 17,000. We propose that chloroplast ferredoxin is synthesized in vitro as a biosynthetic precursor. Ferredoxin synthesis was found to be associated with poly(A)-RNA, which supports our previous conclusion that ferredoxin messenger is a transcript from the DNA of the nucleus. © 1978.