Affiliation:
1. Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111
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.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Cited by
36 articles.
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