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trans-acting inhibition of genomic RNA dimerization by Rous sarcoma virus matrix mutants
R A Garbitt1, J A Albert, M D Kessler
1Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, USA.
Journal of Virology
|December 19, 2000
Summary
Rous sarcoma virus matrix (MA) protein mutants disrupt genomic RNA dimerization via a trans-acting effect. Proper MA protein localization is crucial for RNA dimerization and viral infectivity.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Retroviral genomic RNA exists as a noncovalently linked dimer within the virion.
- A previously identified Rous sarcoma virus matrix (MA) protein mutant, Myr1E, disrupts this viral RNA dimerization.
- Myr1E is N-terminally modified with Src protein amino acids, leading to monomeric RNA production.
Purpose of the Study:
- To distinguish between cis and trans effects of the Myr1E mutant on viral RNA dimerization.
- To investigate the role of MA protein localization in RNA dimerization and viral infectivity.
Main Methods:
- Generated additional mutations (Myr1E.cc, Myr1E-.cc, Myr1E.ATG-) to analyze cis vs. trans effects.
- Assessed viral RNA dimerization and infectivity of mutant viruses.
- Examined subcellular localization of MA-green fluorescent protein fusion proteins.
Main Results:
- Mutations altering RNA sequence (Myr1E.cc, Myr1E-.cc) did not affect viral properties, indicating RNA sequence was not responsible for dimerization defects.
- Myr1E.ATG- mutant showed normal infectivity and dimeric RNA, suggesting the Src sequence itself doesn't prevent dimer formation.
- Wild-type and specific MA mutants displayed distinct subcellular localization patterns compared to Myr1E and Myr1E.cc, implying localization is key.
Conclusions:
- The genomic RNA dimerization defect observed in Myr1E mutants is caused by a trans-acting effect of the mutant MA proteins.
- Proper subcellular localization of the MA protein is essential for both viral RNA dimerization and infectivity.
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