Phage phi80psu3+-directed tyrosine tRNA synthesis in Escherichia coli: effects of T4 phage superinfection on tyrosine suppressor-gene transcription.

Abstract

Infection of Escherichia coli cells with the transducing phage φ80psu+3 causes phage‐dependent synthesis of su+3 tyrosine tRNA. This report describes the effect of superinfecting T4 phages on the expression of a single E. coli tRNA gene, namely the φ80 phage integrated su+3 tyrosine tRNA gene, and provides evidence that T4 phage‐induced alteration of the DNA‐dependent RNA polymerase is sufficient to stop E. coli gene transcription.1. The mutual effects of φ80psu+3 and T4 amN82 phages on their multiplication in E. coli BF266 are as follows: simultaneous infection results in a complete mutual inhibition of phage multiplication; T4 amN82 phage superinfection within 45 min after φ80psu+3 infection has the same result. T4 amN82 phage superinfection later than 45 min after φ80psu+3 phage infection does not affect φ80psu+3 phage multiplication. In all cases of superinfection no viable T4 amN82 phages could be detected, whereas the φ80psu+3 phages multiplied or survived without multiplication.2. The φ80psu+3‐dependent su+3 tyrosine tRNA synthesis is immediately and absolutely inhibited upon T4 amN82 phage superinfection. The cause of this inhibition is not a selective degradation of the φ80 phage‐incorporated su+3 tyrosine tRNA gene, since it could be demonstrated that φ80 phages isolated from lysates of φ80psu+3/T4 amN82 superinfected E. coli cells still carried the suppressor gene.3. The inhibition of φ80psu+3 phage‐dependent su+3 tyrosine tRNA synthesis upon T4 amN82 phage superinfection was also observed if the superinfection with T4 amN82 occurred during inhibition of protein biosynthesis.4. Superinfection of φ80psu+3 phage‐infected E. coli BF266 cells with T4 amN82 ghosts did not inhibit φ80psu+3 phage‐dependent su+3 tyrosine tRNA synthesis.5. The results described above provide evidence that the inhibition of φ80psu+3‐dependent su+3 tyrosine tRNA synthesis upon T4 amN82 phage superinfection is most likely caused by the T4 phage‐induced alteration of the E. coli DNA‐dependent RNA polymerase.