The nus mutations affect transcription termination in Escherichia coli.

The nusA1 and nusB5 mutations in a partial suppression of polarity and thus transcription termination in Escherichia coli. As these mutations block the transcription antitermination activity of bacteriophage lambda N gene product, they paradoxically seem to enhance transcription termination at phage termination sites. The rho mutation HDF026 displays almost identical properties. The observations suggest that the nusA and nusB gene products may act as termination factors analogous to rho protein.