Interference with the expression of the N gene function of phage [lambda] in a mutant of Escherichia coli

Abstract

An Escherichia coli mutant nus, which inhibits the growth of [lambda] by inhibiting the expression of the [lambda] N gene product, has been further characterized. The N protein regulates phage development by stimulating transcription of the [lambda] genome in three ways: directly, by stimulating transcription initiating at the two promoters, PR and PL and indirectly by stimulating the synthesis of Q protein, which in turn activates transcription of late functions. We report in this study that all three types of [lambda] transcription are affected by the nus mutation. However, the inhibitory effect of nus on N stimulation of transcription initiating at PR is shown to be qualitatively different from its effect on N stimulation of the synthesis of Q product.Evidence is also presented showing that some N function is expressed by [lambda] in the nus mutant, but that the level of expression of N function is reduced.