Binding of rho factor to Escherichia coli RNA polymerase mediated by nusA protein

The E. coli transcription termination factor rho binds specifically to purified nusA protein. Since nusA protein binds tightly to RNA polymerase, this provides a way of coupling rho to the elongating RNA polymerase complex through protein-protein interactions. These rho-nusA interactions may play a role in modulating rho action at certain terminators and could also be important in the action of antitermination factors such as lambda N protein.