Modulation of gene expression in E. coli infected with single-stranded bacteriophage φX174

Abstract

Synthesis of tryptophanase, D-serine deaminase and alkaline phosphatase in Escherichia coli C was repressed as the result of infection with the single-stranded DNA bacteriophage φX174. However, the degree of repression differed, the more catabolite-sensitive the operon was, the more severe was the repression. For the catabolite-sensitive enzymes it was found that cyclic adenosine 3'5' monophosphate (cyclic AMP or cAMP) was unable to release or reduce the phage-induced inhibition. Experiments with amber mutants of φX174 revealed that A*, product of cistron A, was responsible for the inhibition. The cistron A product probably acted at the level of transcription. The possible role of A* in the observed modulation of gene expression is discussed.