PROTEIN SYNTHESIS BY A MUTANT OF PHAGE S13 BLOCKED IN DNA SYNTHESIS

Gene IV amber mutants of phage S13 are known to be blocked in the synthesis of progeny replicative form DNA (RF). Protein synthesis by a gene IV mutant has been studied in a nonpermissive host cell strain that permits phage particle formation by the standard phage at doses of ultraviolet radiation that severely depress host protein synthesis. Using gel electrophoresis analysis, it was found that the mutant formed normal amounts of all the six major protein peaks that are observed for the standard phage. (Three of the gel peaks correspond to protein-coat components.) Thus the block in DNA synthesis caused by the gene IV mutation does not switch off either transcription or translation of the majority of the phage genes. Furthermore, parental RF alone is sufficient to produce normal amounts of phage-specific protein. © 1969.