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Published on: October 11, 2013
Rescue of internal scaffold-deleted Mason-Pfizer monkey virus particle production by plasma membrane targeting
Michael Sakalian1, Nathan D Rapp
1Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, Oklahoma City, 73104, USA. mike-sakalian@ouhsc.edu
Abstract:
The Mason-Pfizer monkey virus (M-PMV) Gag protein follows a morphogenesis pathway in which immature capsids are preassembled within the cytoplasm before interaction with and budding through the plasma membrane. Intracytoplasmic assembly is facilitated by sequences within the p12 domain of Gag that we have termed the Internal Scaffold Domain (ISD). If M-PMV utilizes an ISD then what provides the equivalent function for most other retroviruses that assemble at the plasma membrane? To investigate the possibility that the membrane itself fulfills this role, we have combined functional deletion of the ISD with a mutation that disrupts intracellular targeting or with a plasma membrane targeting signal. By either modification, targeting of ISD-deleted Gag to the plasma membrane restores particle production. These results provide support for a model in which the plasma membrane and the D-type ISD provide an interchangeable scaffold-like function in retrovirus assembly.
Insights
Mason-Pfizer monkey virus (M-PMV) Gag protein assembly relies on an Internal Scaffold Domain (ISD). Replacing the ISD with plasma membrane targeting rescues M-PMV particle production, suggesting interchangeable scaffolding functions.
Area of Science:
- Retroviral morphogenesis
- Molecular virology
- Cell biology
Background:
- Mason-Pfizer monkey virus (M-PMV) Gag protein assembly occurs via cytoplasmic preassembly before plasma membrane budding.
- The p12 domain of M-PMV Gag contains an Internal Scaffold Domain (ISD) crucial for intracytoplasmic assembly.
- The role of the plasma membrane in scaffolding assembly for retroviruses lacking a functional ISD is unclear.
Purpose of the Study:
- To investigate the potential scaffolding role of the plasma membrane in retrovirus assembly.
- To determine if the plasma membrane can functionally substitute for the M-PMV Internal Scaffold Domain (ISD).
Main Methods:
- Functional deletion of the M-PMV Gag ISD.
- Introduction of mutations to disrupt intracellular targeting of Gag.
- Addition of a plasma membrane targeting signal to ISD-deleted Gag.
- Analysis of particle production following genetic modifications.
Main Results:
- Targeting ISD-deleted Gag to the plasma membrane restored particle production.
- This indicates that the plasma membrane can provide a scaffolding function.
- The plasma membrane and the M-PMV ISD exhibit interchangeable scaffolding functions in retrovirus assembly.
Conclusions:
- The plasma membrane can serve as an interchangeable scaffold for retrovirus assembly.
- This finding supports a model where both the plasma membrane and the D-type ISD provide essential scaffolding functions.
- This has implications for understanding diverse retroviral morphogenesis pathways.
