INITIATION OF SV40 DNA-DIRECTED PROTEIN SYNTHESIS WITH N-FORMYLMETHIONINE IN VITRO

WE are studying several aspects of the flow of genetic information from DNA to protein with an in vitro system in which RNA synthesis is coupled to protein synthesis. The coupled system, which is prepared from Escherichia coli, is primed with the replicating form of DNA from the bacteriophage φX174. During total asymmetric transcription of the template, several cistrons are translated (refs. 1, 2 and unpublished results of R. N. B. and M. H.). The principal product, which is initiated with N-formyl-methionine, is a φX174 structural protein with a molecular weight of about 20,000. We now demonstrate that DNA from the animal virus SV40 can prime this bacterial system. Two proteins are synthesized, and their estimated molecular weights are about 7,000 and 16,000. The molecular weight of the larger is close to the molecular weight of the SV40 coat protein, 16,350 (ref. 5). Both proteins are initiated with formylmethionine. © 1969 Nature Publishing Group.