Elongation factor Nus G interacts with termination factor ρ to regulate termination and antitermination of transcription

Abstract

NusG is a transcriptional elongation factor in Escherichia coli that aids transcriptional antitermination by the phage λ N protein. By using NusG affinity chromatography, we found that NusG binds directly and selectively to termination factor ρ. NusG was shown previously to be needed for termination by ρ in vivo, and we show here that NusG increases the efficiency of termination by ρ at promoter-proximal sites in vitro. The rho026 mutation makes termination by ρ less dependent on NusG. It also makes antitermination by N at ρ-dependent terminators and the binding of ρ to NusG temperature sensitive. Therefore, the interaction of NusG with ρ is important both for ρ-dependent termination and for antitermination by N at ρ-dependent terminators.