Coat Protein Repression of Bacteriophage M12 RNA Directed Polysome Formation

Phage M12 RNA, serving as a messenger for protein synthesis in vitro , is incorporated into polysomal structures containing up to ten ribosomes per RNA molecule. If this RNA messenger is repressed by M12 coat protein prior to its translation, it binds a maximum of four ribosomes per RNA genome. This difference in polysome distribution is similar to the size difference between phage specific polysomes formed at early and late times of viral development in the infected cell. Such a finding indicates that the theory of translational repression, as it has been proposed from previous experiments in vitro , is also a major control mechanism of phage protein synthesis in vivo .