Dissertation
The role of viral protein kinases in herpes simplex virus type-1
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Summer 2022
DOI: 10.25820/etd.006564
Abstract
Herpesviruses translocate their nucleocapsids from the nucleus to the cytoplasm by capsid envelopment into the inner nuclear membrane and de-envelopment from the outer nuclear membrane, a process that is coordinated by energetically favorable self-association of nuclear egress complex (NEC) proteins, pUL34, and pUL31. Capsid envelopment is associated with alteration in the nuclear architecture and local redistribution of the nuclear lamina. NEC recruits protein kinases, including the virus-encoded protein kinase, pUS3, to the nuclear rim to regulate both lamina redistribution and NEC localization. Examining the role of capsid envelopment in the changes of the nuclear architecture suggests that disruption of the nuclear lamina is a preparation step prior to capsid envelopment. In the absence of capsid envelopment, lamin A/C becomes concentrated at the nuclear envelope in a pUL34-independent and cell type-specific manner, suggesting that ongoing nuclear egress may be required for the dispersal of lamins. pUS3 catalytically-inactive mutants cause accumulation of perinuclear enveloped capsids, formation of NEC aggregates, and enhanced lamina disruption. Interestingly, mutation of US3 in the absence of capsids results in identical NEC aggregation and lamina disruption phenotypes, and NEC aggregates correspond to multi-folded nuclear membrane structures, suggesting that pUS3’s specific role in nuclear egress is to control NEC self-association and membrane deformation. pUS3 is also involved in many other viral and cellular functions, but its regulation is not understood. pUS3-mediated regulation of the NEC is suggested to be selectively regulated by another viral protein kinase, pUL13. However, the comparison of HSV-1 UL13 catalytically-inactive and US3 catalytically-inactive mutants revealed no defined classes of US3 substrates to be UL13-dependent, nor did mutation of UL13 induce a de-envelopment defect like that seen in US3 mutants. Accordingly, mutation of all UL13 kinase motifs in pUS3, individually or in aggregate, does not affect NEC localization, suggesting that pUL13-mediated regulation of the NEC is US3-independent.
Details
- Title: Subtitle
- The role of viral protein kinases in herpes simplex virus type-1
- Creators
- Masoudeh Masoud Bahnamiri
- Contributors
- Richard Roller (Advisor)Wendy Maury (Committee Member)Aloysius Klingelhutz (Committee Member)Lilliana Radoshevich (Committee Member)Ernesto Fuentes (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Microbiology
- Date degree season
- Summer 2022
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.006564
- Number of pages
- xii, 119 pages
- Copyright
- Copyright 2022 Masoudeh Masoud Bahnamiri
- Language
- English
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 103-119).
- Public Abstract (ETD)
Like many viruses, Herpes simplex virus type 1 (HSV-1) enters into a human cell, replicates and packages its genome, and spreads to other cells. HSV-1 is a multi-layer virus including a huge middle shell, called capsid, that encompasses and protects its DNA genome. The capsid is surrounded by a lipid membrane called envelope.
Human cells are compartmentalized with various membrane-closed organelles, and passage of molecules through those membranes takes place via gates that are restricted by the size and weight of those molecules. HSV-1 replicates and packages its DNA into the capsid inside the nuclear compartment. The newly formed HSV-1 genome-containing capsids must exit the nucleus in order to complete their replication cycle and spread, but their size does not allow them to pass through the nuclear gates. Therefore, HSV-1 evolved a pathway to bud through the nuclear membrane called nuclear egress.
Nuclear egress is a complicated multi-step process that is tightly regulated by different viral and cellular factors to achieve the maximum efficiency of capsid translocation to the cytoplasm. In this study, we investigated the mechanism underlying this tight regulation and tested how alteration of one of these regulators affects virus replication. We defined a unifying role for its mechanism of action in different steps of nuclear egress.
- Academic Unit
- Microbiology and Immunology
- Record Identifier
- 9984285051402771
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