InterPro domain: IPR043425

Bacterial transcription antitermination protein, NusG, is a component of the transcription complex and interacts with the termination factor Rho and RNA polymerase [ 1 , 2 ]. NusG is a bacterial transcriptional elongation factor involved in transcription termination and anti-termination [ 3 ].

This entry includes NusG and RfaH.

RfaH is a transcription antitermination protein that enhances distal genes transcription elongation in a specialized subset of operons that encode extracytoplasmic components [ 4 ]. It is most closely related to the transcriptional termination/antitermination protein NusG and contains the KOW motif [ 5 ]. This protein appears to be limited to the proteobacteria.

RfaH is recruited into a multi-component RNA polymerase complex by the ops element, which is a short conserved DNA sequence located downstream of the main promoter of these operons. Once bound, RfaH suppresses pausing and inhibits Rho-dependent and intrinsic termination at a subset of sites. Termination signals are bypassed, which allows complete synthesis of long RNA chains. Enhances expression of several operons involved in synthesis of lipopolysaccharides, exopolysaccharides, hemolysin, and sex factor. Also negatively controls expression and surface presentation of AG43 and possibly another AG43-independent factor that mediates cell-cell interactions and biofilm formation [ 6 , 6 , 7 ].

1. Elongation factor NusG interacts with termination factor rho to regulate termination and antitermination of transcription. Genes Dev. 7, 161-72
2. NusG, a new Escherichia coli elongation factor involved in transcriptional antitermination by the N protein of phage lambda. J. Biol. Chem. 267, 6012-9
3. NusG alters rho-dependent termination of transcription in vitro independent of kinetic coupling. Gene Expr. 3, 119-33
4. The transcriptional regulator RfaH stimulates RNA chain synthesis after recruitment to elongation complexes by the exposed nontemplate DNA strand. Cell 109, 193-203
5. KOW: a novel motif linking a bacterial transcription factor with ribosomal proteins. Trends Biochem. Sci. 21, 425-6
6. RfaH, a bacterial transcription antiterminator. Mol. Cell 9, 698-700
7. The transcriptional antiterminator RfaH represses biofilm formation in Escherichia coli. J. Bacteriol. 188, 1316-31