F factor-mediated inhibition of bacteriophage T7 growth: analysis of T7 RNA and protein synthesis in vivo and in vitro using male and female Escherichia coli.

Abstract

We have used two approaches to determine whether the inhibition of phage T7 growth by the F factor in male Escherichia coli can be ascribed to a preferential inhibition of late phage protein synthesis. (1) Proteins and RNAs were pulselabeled with [ 35 S]methionine and 32 PO 4 2− during T7 infection of male and female E. coli , and the products were analyzed by polyacrylamide gel electrophoresis. Compared to T7 infected female E. coli , a simultaneous inhibition of protein and RNA synthesis is observed in male cells between eight and ten minutes after infection at 30°C. (2) Late T7 proteins were labeled with [ 35 S]methionine in a DNA-dependent coupled in vitro protein synthesizing system using extracts from uninfected and T7 infected male and female E. coli and analyzed by polyacrylamide gel electrophoresis. Under conditions where faithful synthesis of 16 out of 20 phage proteins is directed by T7 DNA in vitro , extracts derived from uninfected or T7-infected male E. coli are fully active in phage-specific transcription and translation. We therefore conclude that the cessation of RNA and protein synthesis in T7-infected male E. coli cannot be directly ascribed to any specific modification or inhibition of the transcription or translation apparatus.