Summary for 9YF8
| Entry DOI | 10.2210/pdb9yf8/pdb |
| EMDB information | 72880 |
| Descriptor | Probable portal protein (1 entity in total) |
| Functional Keywords | dodecamer, bacteriophage portal, viral protein |
| Biological source | Escherichia phage N4 |
| Total number of polymer chains | 12 |
| Total formula weight | 1027710.28 |
| Authors | |
| Primary citation | Bellis, N.F.,Lokareddy, R.K.,Pavlenok, M.,Horton, S.L.C.,Kizziah, J.L.,Forti, F.,Schneider, D.A.,Niederweis, M.,Briani, F.,Cingolani, G. Structure of the giant RNA polymerase ejected from coliphage N4. Res Sq, 2025 Cited by PubMed Abstract: are widespread prokaryotic viruses that encapsidate a giant (~3,500-residue) virion-associated RNA polymerase (vRNAP). During infection, vRNAP is expelled into Gram-negative bacteria, along with two additional ejection proteins, to assemble a transient DNA-ejectosome that becomes transcriptionally active, initiating viral replication. Here, we present an integrative structural analysis of the coliphage N4 vRNAP (gp50). We find that this 383 kDa enzyme is a multi-domain, single-chain RNA polymerase, structurally distinct from both compact single-chain RNAPs and large multi-subunit holoenzymes. vRNAP is composed of loosely connected domains and exhibits an intramolecular mode of allosteric regulation through its C-terminal domain. Comparative analysis of intact and genome-released virions identified gp51, which forms an outer-membrane complex, and gp52, which assembles a periplasmic tunnel. These proteins generate heterogeneous pores that facilitate the release of vRNAP. We further uncover a signaling hub in the phage tail, composed of the receptor-binding protein, tail tube, and tail plug, that detects receptor engagement and orchestrates the release of ejection proteins. We propose that the beads-on-a-string architecture of vRNAP enables the translocation of megadalton-scale protein complexes through the ~35 Å channel formed by the tail and ejection proteins. These findings establish N4 as a distinctive model for protein translocation through biological channels. PubMed: 41282253DOI: 10.21203/rs.3.rs-7746245/v1 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.9 Å) |
Structure validation
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