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Rhabdoviruses and the cellular ubiquitin-proteasome system: a budding interaction.
R N Harty1, M E Brown, J P McGettigan
1Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, 19104, USA. rharty@vet.upenn.edu
Journal of Virology
|October 17, 2001
Summary
The cellular ubiquitin-proteasome system is crucial for vesicular stomatitis virus (VSV) and rabies virus (RV) budding. Inhibiting this system significantly reduces viral titers, highlighting its role in rhabdovirus replication.
Area of Science:
- Virology
- Molecular Biology
- Cellular Biology
Background:
- Matrix (M) proteins of vesicular stomatitis virus (VSV) and rabies virus (RV) are essential for progeny virion assembly and budding.
- A conserved PPPY motif (PY motif) in M proteins mediates interactions with cellular WW domain-containing proteins, crucial for virus budding.
Purpose of the Study:
- To identify cellular interactors of the VSV M protein's PY motif.
- To investigate the role of the ubiquitin-proteasome system in VSV and RV budding.
Main Methods:
- Screening a mouse embryo cDNA library using the VSV M protein PY motif as bait.
- Identifying and characterizing the interaction between VSV M protein and mouse Nedd4 protein.
- Assessing the interaction and ubiquitination of VSV M protein by yeast Nedd4 homolog Rsp5.
- Treating infected cells with proteasome inhibitors (MG132) and measuring viral titers.
- Analyzing the budding of a VSV PY mutant in the presence of MG132.
Main Results:
- Mouse Nedd4, a ubiquitin ligase, was identified as a VSV M protein interactor.
- Yeast Rsp5 (Nedd4 homolog) physically and functionally interacted with VSV M protein in a PY-dependent manner, leading to M protein multiubiquitination.
- Proteasome inhibitor treatment reduced VSV and RV viral titers by 10- to 20-fold.
- MG132 did not inhibit the budding of a VSV PY mutant, indicating the PY motif's requirement for this effect.
Conclusions:
- The cellular ubiquitin-proteasome machinery is involved in the budding process of VSV and RV.
- The PY motif of the VSV M protein is essential for the inhibitory effect of proteasome inhibition on virus budding.
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