9MKB

Structure of the bacteriophage T4 portal-neck-tail complex

This is a non-PDB format compatible entry.

Summary for 9MKB

• Entry DOI: 10.2210/pdb9mkb/pdb
• EMDB information: 48324
• Descriptor: gp14, neck protein, Hoc, highly immunogenic outer capsid protein, Soc, small outer capsid protein, ... (32 entities in total)
• Functional Keywords: bacteriophage t4, portal vertex, phage neck, phage tail, contractile sheath, tail tube, baseplate, virus, viral protein
• Biological source: Escherichia phage T4; More
• Total number of polymer chains: 541
• Total formula weight: 24141063.30

Authors

Fokine, A.,Zhu, J.,Klose, T.,Vago, F.,Arnaud, C.,Wang, Z.,Khare, B.,Rossmann, M.G.,Chen, Z.,Sun, L.,Fang, Q.,Kuhn, R.,Rao, V.B. (deposition date: 2024-12-17, release date: 2025-12-24, Last modification date: 2026-07-08)

Primary citation

Fokine, A.,Zhu, J.,Klose, T.,Vago, F.,Arnaud, C.A.,Wang, Z.,Khare, B.,Rossmann, M.G.,Chen, Z.,Sun, L.,Fang, Q.,Kuhn, R.J.,Rao, V.B.
In situ structures of the portal-neck-tail complex of bacteriophage T4 inform a viral genome positioning mechanism.
Nat Commun, 17:-, 2026

PubMed Abstract: The post-genome packaging mechanisms that govern the assembly of an infectious virion are poorly understood in bacteriophages and other viruses. Here, our near-atomic resolution cryo-EM structural analyses uncovered an assembly- and conformation-driven genome positioning mechanism in the tailed bacteriophage T4. We show that following headful packaging, which generates a pressurized head, a global conformational change occurs in the portal structure, probably triggering packaging termination and ejection of the packaging motor. Our high-resolution structures of the neck of the virion further show that the neck undergoes conformational changes upon docking of a pre-assembled tail onto the sealed neck, which then opens a genome-gate. Driven by the pressure of the packaged DNA, the genome travels through open neck channels, binds and compresses the resident tape-measure protein, and halts at the bottom of the second topmost disk of the tail tube. Pressure-suspended within the virion's innermost tunnel and secured by a baseplate plug, the genome remains poised to flow through the tunnel into a host cell upon receiving the host receptor recognition signal.

PubMed: 41720772
DOI: 10.1038/s41467-026-69106-8

Experimental method

ELECTRON MICROSCOPY (3.8 Å)