Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids

Abstract Tailed bacteriophages are one of the most numerous and diverse group of viruses. They store their genome at quasi-crystalline densities in capsids built from multiple copies of proteins adopting the HK97-fold. The high density of the genome exerts an internal pressure, requiring a maturatio...

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Main Authors: Jennifer M. Podgorski, Joshua Podgorski, Lawrence Abad, Deborah Jacobs-Sera, Krista G. Freeman, Colin Brown, Graham F. Hatfull, Antoni Luque, Simon J. White
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-58298-0
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author Jennifer M. Podgorski
Joshua Podgorski
Lawrence Abad
Deborah Jacobs-Sera
Krista G. Freeman
Colin Brown
Graham F. Hatfull
Antoni Luque
Simon J. White
author_facet Jennifer M. Podgorski
Joshua Podgorski
Lawrence Abad
Deborah Jacobs-Sera
Krista G. Freeman
Colin Brown
Graham F. Hatfull
Antoni Luque
Simon J. White
author_sort Jennifer M. Podgorski
collection DOAJ
description Abstract Tailed bacteriophages are one of the most numerous and diverse group of viruses. They store their genome at quasi-crystalline densities in capsids built from multiple copies of proteins adopting the HK97-fold. The high density of the genome exerts an internal pressure, requiring a maturation process that reinforces their capsids. However, it is unclear how capsid stabilization strategies have adapted to accommodate the evolution of larger genomes in this virus group. Here we characterize a capsid reinforcement mechanism in two evolutionary-related actinobacteriophages that modifies the length of a stabilization protein to accommodate a larger genome while maintaining the same capsid size. We use cryo-EM to reveal that capsids contain split hexamers of HK97-fold proteins with a stabilization protein in the chasm. The observation of split hexamers in mature capsids is unprecedented, so we rationalize this result mathematically, discovering that icosahedral capsids can be formed by all split or skewed hexamers as long as their T-number is not a multiple of three. Our results suggest that analogous stabilization mechanisms can be present in other icosahedral capsids, and they provide a strategy for engineering capsids accommodating larger DNA cargoes as gene delivery systems.
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spelling doaj-art-48f1dd02ae2b47f9bd71da3d706c1ec72025-08-20T04:02:57ZengNature PortfolioNature Communications2041-17232025-04-0116111010.1038/s41467-025-58298-0Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsidsJennifer M. Podgorski0Joshua Podgorski1Lawrence Abad2Deborah Jacobs-Sera3Krista G. Freeman4Colin Brown5Graham F. Hatfull6Antoni Luque7Simon J. White8Biology/Physics Building, Department of Molecular and Cell Biology, University of ConnecticutBiology/Physics Building, Department of Molecular and Cell Biology, University of ConnecticutDepartment of Biological Sciences, University of PittsburghDepartment of Biological Sciences, University of PittsburghDepartment of Biological Sciences, University of PittsburghDepartment of Physics, San Diego State UniversityDepartment of Biological Sciences, University of PittsburghDepartment of Biology, University of MiamiBiology/Physics Building, Department of Molecular and Cell Biology, University of ConnecticutAbstract Tailed bacteriophages are one of the most numerous and diverse group of viruses. They store their genome at quasi-crystalline densities in capsids built from multiple copies of proteins adopting the HK97-fold. The high density of the genome exerts an internal pressure, requiring a maturation process that reinforces their capsids. However, it is unclear how capsid stabilization strategies have adapted to accommodate the evolution of larger genomes in this virus group. Here we characterize a capsid reinforcement mechanism in two evolutionary-related actinobacteriophages that modifies the length of a stabilization protein to accommodate a larger genome while maintaining the same capsid size. We use cryo-EM to reveal that capsids contain split hexamers of HK97-fold proteins with a stabilization protein in the chasm. The observation of split hexamers in mature capsids is unprecedented, so we rationalize this result mathematically, discovering that icosahedral capsids can be formed by all split or skewed hexamers as long as their T-number is not a multiple of three. Our results suggest that analogous stabilization mechanisms can be present in other icosahedral capsids, and they provide a strategy for engineering capsids accommodating larger DNA cargoes as gene delivery systems.https://doi.org/10.1038/s41467-025-58298-0
spellingShingle Jennifer M. Podgorski
Joshua Podgorski
Lawrence Abad
Deborah Jacobs-Sera
Krista G. Freeman
Colin Brown
Graham F. Hatfull
Antoni Luque
Simon J. White
Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
Nature Communications
title Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
title_full Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
title_fullStr Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
title_full_unstemmed Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
title_short Stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
title_sort stabilization mechanism accommodating genome length variation in evolutionarily related viral capsids
url https://doi.org/10.1038/s41467-025-58298-0
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