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A large region within the Rous sarcoma virus matrix protein is dispensable for budding and infectivity
1Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
Abstract:
All retroviruses have a layer of matrix protein (MA) situated directly beneath the lipid of their envelope. This protein is initially expressed as the amino-terminal sequence of the Gag polyprotein, where it plays an important role in binding Gag to the plasma membrane during the early steps of the budding process. Others have suggested that MA may provide additional functions during virion assembly, including the selective incorporation of viral glycoproteins and the RNA genome into the emerging virion. To further study the role of the Rous sarcoma virus MA sequence in the viral replication cycle, we have pursued an extensive deletion analysis. Surprisingly, the entire second half of MA (residues 87 to 155) and part of the neighboring p2 sequence were found to be dispensable not only for budding but also for infectivity in avian cells. Thus, all of the functions associated with the Rous sarcoma virus MA sequence must be contained within its first half.
Insights
The matrix protein (MA) of Rous sarcoma virus is crucial for viral replication. Extensive deletion analysis reveals that only the first half of MA is essential for viral budding and infectivity in avian cells.
Area of Science:
- Virology
- Molecular Biology
- Retroviral Research
Background:
- Retroviruses possess a matrix protein (MA) layer beneath the envelope.
- MA is the amino-terminal sequence of the Gag polyprotein.
- MA mediates Gag binding to the plasma membrane during viral budding.
Purpose of the Study:
- Investigate the role of Rous sarcoma virus MA sequence in the viral replication cycle.
- Determine the functional domains of the MA sequence.
- Identify essential regions for viral budding and infectivity.
Main Methods:
- Extensive deletion analysis of the Rous sarcoma virus MA sequence.
- Assessing viral budding efficiency.
- Evaluating viral infectivity in avian cells.
Main Results:
- The entire second half of the MA sequence (residues 87 to 155) is dispensable for viral budding.
- Part of the neighboring p2 sequence is also dispensable.
- The identified dispensable regions do not affect infectivity in avian cells.
Conclusions:
- All essential functions of the Rous sarcoma virus MA sequence are contained within its first half.
- The second half of MA and part of p2 are not required for viral replication.
- This finding narrows down the critical functional regions of the MA protein.