title: Evidence for the presence of nontranslated T7 late mRNA in infected F'(PIF+) episome-containing cells.
abstract: The inability of T7 to develop in cells of Escherichia coli containing F(+) or substituted F' episomes is a result of the failure to synthesize late proteins; no in vivo translation of mRNA species synthesized by the T7 RNA polymerase occurs. Further experiments have been performed to measure the amount of late mRNA in T7-infected F'(PIF(+)) cells. (We have designated the property of phage inhibition of F factors as PIF; the wild-type episome is therefore F'[PIF(+)].) T7 late proteins were synthesized in vitro by using a system programed with RNA extracted from T7-infected F(-) and F'(PIF(+)) cells. The T7 lysozyme, product of gene 3.5, and the gene 10 head protein were assayed. The following results were obtained: (i) mRNA capable of supporting in vitro synthesis of lysozyme and the gene 10 head protein is present in T7-infected F'(PIF(+)) cells; (ii) lysozyme mRNA extracted from T7-infected F'(PIF(+)) cells is present at 70 to 75% of the level found in T7-infected F(-) cells; (iii) gene 10 mRNA is present at 35 to 78% of the level found in T7-infected F(-) cells. No in vivo synthesis of either lysozyme or gene 10 protein can be detected in T7-infected F'(PIF(+)) cells although normal synthesis of these proteins occurs in F(-) cells. These findings confirm that the block in T7 development in F'(PIF(+)) cells results from the failure to translate late classes of T7 RNA.
mesh_terms: D002474:Cell-Free System; D003090:Coliphages / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000166:cytology / Q000378:metabolism; D005796:Genes; D005827:Genetics, Microbial; D008239:Lysine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D009113:Muramidase / Q000096:biosynthesis; D009154:Mutation; D010867:Pimelic Acids / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D014316:Tritium; D014764:Viral Proteins / Q000096:biosynthesis
chemical_list: D010867:Pimelic Acids; D012333:RNA, Messenger; D012367:RNA, Viral; D013462:Sulfur Radioisotopes; D014764:Viral Proteins; D014316:Tritium; D008715:Methionine; D009113:Muramidase; D008239:Lysine