Structural highlights
Function
[D13_VACCW] Scaffold protein which forms a transitory spherical honeycomb lattice providing curvature and rigidity to the convex membrane of crescent and immature virions (IV). This association occurs concomitantly with viral membrane formation. Targeted by the drug rifampicin, which prevents the formation of this lattice, and hence virus morphogenesis. In the presence of rifampicin, irregularly shaped membranes that lack the honeycomb layer accumulate around areas of electron-dense viroplasm. This layer is lost from virions during maturation from IV to mature virion (MV), through the proteolysis of A17 N-terminus.
Publication Abstract from PubMed
In Vaccinia virus (VACV), the prototype poxvirus, scaffold protein D13 forms a honeycomb-like lattice on the viral membrane that results in formation of the pleomorphic immature virion (IV). The structure of D13 is similar to those of major capsid proteins that readily form icosahedral capsids in nucleocytoplasmic large DNA viruses (NCLDVs). However, the detailed assembly mechanism of the nonicosahedral poxvirus scaffold has never been understood. Here we show the cryo-EM structures of the D13 trimer and scaffold intermediates produced in vitro. The structures reveal that the displacement of the short N-terminal alpha-helix is critical for initiation of D13 self-assembly. The continuous curvature of the IV is mediated by electrostatic interactions that induce torsion between trimers. The assembly mechanism explains the semiordered capsid-like arrangement of D13 that is distinct from icosahedral NCLDVs. Our structures explain how a single protein can self-assemble into different capsid morphologies and represent a local exception to the universal Caspar-Klug theory of quasi-equivalence.
Assembly mechanism of the pleomorphic immature poxvirus scaffold.,Hyun J, Matsunami H, Kim TG, Wolf M Nat Commun. 2022 Mar 31;13(1):1704. doi: 10.1038/s41467-022-29305-5. PMID:35361762[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hyun J, Matsunami H, Kim TG, Wolf M. Assembly mechanism of the pleomorphic immature poxvirus scaffold. Nat Commun. 2022 Mar 31;13(1):1704. doi: 10.1038/s41467-022-29305-5. PMID:35361762 doi:http://dx.doi.org/10.1038/s41467-022-29305-5
