A pentameric protein ring with novel architecture is required for herpesviral packaging
Abstract
Genome packaging in large double-stranded DNA viruses requires a powerful molecular motor to force the viral genome into nascent capsids, which involves essential accessory factors that are poorly understood. Here, we present structures of two such accessory factors from the oncogenic herpesviruses Kaposi's sarcoma-associated herpesvirus (KSHV; ORF68) and Epstein-Barr virus (EBV; BFLF1). These homologous proteins form highly similar homopentameric rings with a positively charged central channel that binds double-stranded DNA. Mutation of individual positively charged residues within but not outside the channel ablates DNA binding, and in the context of KSHV infection these mutants fail to package the viral genome or produce progeny virions. Thus, we propose a model in which ORF68 facilitates the transfer of newly replicated viral genomes to the packaging motor.
Data availability
Atomic coordinates and structure factors for ORF68 have been deposited in the Protein Data Bank with accession code 6XF9. Diffraction images have been deposited in the SBGrid Data Bank under ID 794 (https://doi:10.15785/SBGRID/794). Cryo-EM maps for ORF68 and BFLF1 have been deposited in the Electron Microscopy Data Bank with accession codes EMD-22167 and EMD-22168. The atomic model of BFLF1 was deposited in the Protein Data Bank with accession code 6XFA. Final coordinate sets, structure factors with calculated phases, and cryo-EM maps are provided as Supplementary Data 1.
Article and author information
Author details
Funding
Damon Runyon Cancer Research Foundation (DRG-2349-18)
- Allison L Didychuk
Damon Runyon Cancer Research Foundation (DRG-2342-18)
- Stephanie N Gates
Howard Hughes Medical Institute (n/a)
- Andreas Martin
- Britt A Glaunsinger
National Institutes of Health (R01AI122528)
- Britt A Glaunsinger
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Didychuk et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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