3LJ5: Full Length Bacteriophage P22 Portal Protein

DNA viruses such as bacteriophages and herpesviruses deliver their genome into and out of the capsid through large proteinaceous assemblies, known as portal proteins. Here, we report two snapshots of the dodecameric portal protein of bacteriophage P22. The 3.25-A-resolution structure of the portal-protein core bound to 12 copies of gene product 4 (gp4) reveals a ~1.1-MDa assembly formed by 24 proteins. Unexpectedly, a lower-resolution structure of the full-length portal protein unveils the unique topology of the C-terminal domain, which forms a ~200-A-long alpha-helical barrel. This domain inserts deeply into the virion and is highly conserved in the Podoviridae family. We propose that the barrel domain facilitates genome spooling onto the interior surface of the capsid during genome packaging and, in analogy to a rifle barrel, increases the accuracy of genome ejection into the host cell.
PDB ID: 3LJ5Download
MMDB ID: 89978
PDB Deposition Date: 2010/1/25
Updated in MMDB: 2011/05
Experimental Method:
x-ray diffraction
Resolution: 7.5  Å
Source Organism:
Similar Structures:
Biological Unit for 3LJ5: dodecameric; determined by author and by software (PISA)
Molecular Components in 3LJ5
Label Count Molecule
Proteins (12 molecules)
Portal Protein(Gene symbol: 1)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB