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| Title | Sm-like protein Rof inhibits transcription termination factor ρ by binding site obstruction and conformational insulation. |
|---|---|
| Journal, issue, pages | Nat Commun, Vol. 15, Issue 1, Page 3186, Year 2024 |
| Publish date | Apr 15, 2024 |
 Authors | Nelly Said / Mark Finazzo / Tarek Hilal / Bing Wang / Tim Luca Selinger / Daniela Gjorgjevikj / Irina Artsimovitch / Markus C Wahl /    |
| PubMed Abstract | Transcription termination factor ρ is a hexameric, RNA-dependent NTPase that can adopt active closed-ring and inactive open-ring conformations. The Sm-like protein Rof, a homolog of the RNA ...Transcription termination factor ρ is a hexameric, RNA-dependent NTPase that can adopt active closed-ring and inactive open-ring conformations. The Sm-like protein Rof, a homolog of the RNA chaperone Hfq, inhibits ρ-dependent termination in vivo but recapitulation of this activity in vitro has proven difficult and the precise mode of Rof action is presently unknown. Here, our cryo-EM structures of ρ-Rof and ρ-RNA complexes show that Rof undergoes pronounced conformational changes to bind ρ at the protomer interfaces, undercutting ρ conformational dynamics associated with ring closure and occluding extended primary RNA-binding sites that are also part of interfaces between ρ and RNA polymerase. Consistently, Rof impedes ρ ring closure, ρ-RNA interactions and ρ association with transcription elongation complexes. Structure-guided mutagenesis coupled with functional assays confirms that the observed ρ-Rof interface is required for Rof-mediated inhibition of cell growth and ρ-termination in vitro. Bioinformatic analyses reveal that Rof is restricted to Pseudomonadota and that the ρ-Rof interface is conserved. Genomic contexts of rof differ between Enterobacteriaceae and Vibrionaceae, suggesting distinct modes of Rof regulation. We hypothesize that Rof and other cellular anti-terminators silence ρ under diverse, but yet to be identified, stress conditions when unrestrained transcription termination by ρ may be detrimental. |
 External links | Nat Commun / PubMed:38622114 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 2.7 - 3.3 Å |
| Structure data | EMDB-17870, PDB-8ptg: EMDB-17874, PDB-8ptm: EMDB-17875, PDB-8ptn: EMDB-17876, PDB-8pto: EMDB-17877, PDB-8ptp: |
| Chemicals |  ChemComp-ADP:  ChemComp-MG:  ChemComp-BEF: |
| Source |
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 Keywords |  TRANSCRIPTION / Transcription termination factor Rho Inhibition of termination Sm-like protein Rof Rho regulation / TRANSCRIPTION RNA binding PBS SBS / Transcription termination factor Rho Transcription inhibition Sm-like protein Rof Rho regulation |
