THE DNA-REPLICATION FORK CAN PASS RNA-POLYMERASE WITHOUT DISPLACING THE NASCENT TRANSCRIPT

Replication proteins encoded by bacteriophage T4 generate DNA replicat ion forks that can pass a molecule of Escherichia coli RNA polymerase moving in the same direction as the fork in vitro. The RNA polymerase ternary transcription complex remains bound to the DNA and retains a t ranscription bubble after the fork passes. The by-passed ternary compl ex can resume faithful RNA synthesis, suggesting that the multisubunit RNA polymerase of E. coli has evolved to retain its transcript after DNA replication, allowing partially completed transcripts to be elonga ted into full-length RNA molecules.