Antitermination of transcription by the N-gene protein of bacteriophage lambda: recent progress and remaining problems.

The N-gene protein of bacteriophage lambda recognizes sequences called nut in the lambda early operons and acts to prevent termination of the transcription of these operons. Part of the mechanism of action of N protein involves binding to the nusA protein of Escherichia coli, a transcription termination factor which associates directly with RNA polymerase. It is likely that N protein forms a ternary complex with the nusA protein and RNA polymerase at the nut site. Evidence is presented that translating ribosomes are not involved in N-protein action. It is still not known how RNA polymerase is modified to become termination-resistent as a result of N protein action.