5jj3

From Proteopedia

Refined Structure of the Mature Virion Conformation of P22 Portal Protein

PDB ID 5jj3

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Structural highlights

5jj3 is a 12 chain structure with sequence from Salmonella virus P22. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 7Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

PORTL_BPP22 Required for successful condensation of DNA within the capsid. Gp1 is a minor structural protein. The portal protein is present as a single ring-shaped dodecamer located at the point where tails attach. It is through this ring that DNA is thought to enter the prohead.

Publication Abstract from PubMed

Tailed bacteriophages and herpesviruses assemble infectious particles via an empty precursor capsid (or 'procapsid') built by multiple copies of coat and scaffolding protein and by one dodecameric portal protein. Genome packaging triggers rearrangement of the coat protein and release of scaffolding protein, resulting in dramatic procapsid lattice expansion. Here, we provide structural evidence that the portal protein of the bacteriophage P22 exists in two distinct dodecameric conformations: an asymmetric assembly in the procapsid (PC-portal) that is competent for high affinity binding to the large terminase packaging protein, and a symmetric ring in the mature virion (MV-portal) that has negligible affinity for the packaging motor. Modelling studies indicate the structure of PC-portal is incompatible with DNA coaxially spooled around the portal vertex, suggesting that newly packaged DNA triggers the switch from PC- to MV-conformation. Thus, we propose the signal for termination of 'Headful Packaging' is a DNA-dependent symmetrization of portal protein.

Portal protein functions akin to a DNA-sensor that couples genome-packaging to icosahedral capsid maturation.,Lokareddy RK, Sankhala RS, Roy A, Afonine PV, Motwani T, Teschke CM, Parent KN, Cingolani G Nat Commun. 2017 Jan 30;8:14310. doi: 10.1038/ncomms14310. PMID:28134243^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Lokareddy RK, Sankhala RS, Roy A, Afonine PV, Motwani T, Teschke CM, Parent KN, Cingolani G. Portal protein functions akin to a DNA-sensor that couples genome-packaging to icosahedral capsid maturation. Nat Commun. 2017 Jan 30;8:14310. doi: 10.1038/ncomms14310. PMID:28134243 doi:http://dx.doi.org/10.1038/ncomms14310