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UL25 capsid binding facilitates mechanical maturation of the Herpesvirus capsid and allows retention of pressurized DNA

Freeman, Krista G ; Huffman, Jamie B ; Homa, Fred L and Evilevitch, Alex LU orcid (2021) In Journal of Virology 95(20).
Abstract

The maturation process that occurs in most viruses is evolutionarily driven as it resolves several conflicting virion assembly requirements. During herpesvirus assembly in a host cell nucleus, micron-long double-stranded herpes DNA is packaged into a nanometer-sized procapsid. This leads to strong confinement of the viral genome with resulting tens of atmospheres of intra-capsid DNA pressure. Yet, the procapsid is unstable due to weak, reversible interactions between its protein subunits, which ensures free energy minimization and reduces assembly errors. In this work we show that herpesviruses resolve these contradictory capsid requirements through a mechanical capsid maturation process facilitated by multi-functional auxiliary protein... (More)

The maturation process that occurs in most viruses is evolutionarily driven as it resolves several conflicting virion assembly requirements. During herpesvirus assembly in a host cell nucleus, micron-long double-stranded herpes DNA is packaged into a nanometer-sized procapsid. This leads to strong confinement of the viral genome with resulting tens of atmospheres of intra-capsid DNA pressure. Yet, the procapsid is unstable due to weak, reversible interactions between its protein subunits, which ensures free energy minimization and reduces assembly errors. In this work we show that herpesviruses resolve these contradictory capsid requirements through a mechanical capsid maturation process facilitated by multi-functional auxiliary protein UL25. Through mechanical interrogation of herpes simplex virus type 1 (HSV-1) capsid with atomic force microscopy nano-indentation, we show that UL25 binding at capsid vertices post-assembly provides the critical capsid reinforcement required for stable DNA encapsidation; the absence of UL25 binding leads to capsid rupture. Furthermore, we demonstrate that gradual capsid reinforcement is a feasible maturation mechanism facilitated by progressive UL25 capsid binding, which is likely correlated with DNA packaging progression. This work provides insight into elegantly programmed viral assembly machinery where targeting of capsid assembly mechanics presents a new antiviral strategy that is resilient to development of drug resistance. Importance: Most viruses undergo a maturation process from a weakly assembled particle to a stable virion. Herpesvirus capsid undergoes mechanical maturation to withstand tens of atmospheres of DNA pressure. We demonstrate that this mechanical capsid maturation is mainly facilitated through binding of auxiliary protein UL25 in HSV-1 capsid vertices. We show that UL25 binding provides the critical capsid reinforcement required for stable DNA encapsidation. Our data also suggests that gradual capsid reinforcement by progressive UL25 binding is a feasible capsid maturation mechanism, correlated with DNA packaging progression.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Virology
volume
95
issue
20
article number
e00755-21
publisher
American Society for Microbiology
external identifiers
  • scopus:85116343955
  • pmid:34346766
ISSN
1098-5514
DOI
10.1128/JVI.00755-21
language
English
LU publication?
yes
id
53b052fa-fd5e-4b30-a5cf-f35f3ab7ff22
date added to LUP
2021-08-16 16:07:20
date last changed
2024-04-20 09:26:18
@article{53b052fa-fd5e-4b30-a5cf-f35f3ab7ff22,
  abstract     = {{<p>The maturation process that occurs in most viruses is evolutionarily driven as it resolves several conflicting virion assembly requirements. During herpesvirus assembly in a host cell nucleus, micron-long double-stranded herpes DNA is packaged into a nanometer-sized procapsid. This leads to strong confinement of the viral genome with resulting tens of atmospheres of intra-capsid DNA pressure. Yet, the procapsid is unstable due to weak, reversible interactions between its protein subunits, which ensures free energy minimization and reduces assembly errors. In this work we show that herpesviruses resolve these contradictory capsid requirements through a mechanical capsid maturation process facilitated by multi-functional auxiliary protein UL25. Through mechanical interrogation of herpes simplex virus type 1 (HSV-1) capsid with atomic force microscopy nano-indentation, we show that UL25 binding at capsid vertices post-assembly provides the critical capsid reinforcement required for stable DNA encapsidation; the absence of UL25 binding leads to capsid rupture. Furthermore, we demonstrate that gradual capsid reinforcement is a feasible maturation mechanism facilitated by progressive UL25 capsid binding, which is likely correlated with DNA packaging progression. This work provides insight into elegantly programmed viral assembly machinery where targeting of capsid assembly mechanics presents a new antiviral strategy that is resilient to development of drug resistance. Importance: Most viruses undergo a maturation process from a weakly assembled particle to a stable virion. Herpesvirus capsid undergoes mechanical maturation to withstand tens of atmospheres of DNA pressure. We demonstrate that this mechanical capsid maturation is mainly facilitated through binding of auxiliary protein UL25 in HSV-1 capsid vertices. We show that UL25 binding provides the critical capsid reinforcement required for stable DNA encapsidation. Our data also suggests that gradual capsid reinforcement by progressive UL25 binding is a feasible capsid maturation mechanism, correlated with DNA packaging progression.</p>}},
  author       = {{Freeman, Krista G and Huffman, Jamie B and Homa, Fred L and Evilevitch, Alex}},
  issn         = {{1098-5514}},
  language     = {{eng}},
  month        = {{08}},
  number       = {{20}},
  publisher    = {{American Society for Microbiology}},
  series       = {{Journal of Virology}},
  title        = {{UL25 capsid binding facilitates mechanical maturation of the Herpesvirus capsid and allows retention of pressurized DNA}},
  url          = {{http://dx.doi.org/10.1128/JVI.00755-21}},
  doi          = {{10.1128/JVI.00755-21}},
  volume       = {{95}},
  year         = {{2021}},
}