NusG protein couples transcription with
NusG represents conserved transcription factor homologous to eukaryotic Spt5, bridging transcription and translation machineries in bacteria. N-terminal NG domain binds clamp helices of RNA polymerase increasing elongation processivity, while C-terminal KOW domain interacts with ribosomal protein NusE/S10 linking lead ribosome to polymerase during coupled transcription-translation. This physical tether prevents Rho from accessing nascent RNA, suppresses premature termination, and maintains reading frame coupling. NusG also influences DNA repair through interaction with UvrD. Thus primary described function remains coupling transcription apparatus with ribosomal translation ensuring mRNA surveillance and efficient gene expression coordination.
Ref: Alberts Chapter 6: NusG couples transcription with translation coupling mechanism; Nature 2020 Structure NusG bridging RNAP-ribosome; Lodish Chapter 8 Coupling