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Point mutations in Moloney murine leukemia virus envelope protein: effects on infectivity, virion association, and
1Howard Hughes Medical Institute, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Abstract:
Retroviral envelope proteins are synthesized in the infected cell and targetted to the assembling virion; during infection, they mediate receptor binding and fusion of the virion and cell membranes. We have generated a series of mutants of the Moloney murine leukemia virus (M-MuLV) with alterations in the TM protein, p15E, and determined whether the mutants are defective for replication and where the defects lie. Twenty-one point mutants were assessed for infectivity, virion-associated envelope protein levels, and the ability to confer resistance to superinfection. Only one mutant was specifically defective in a post-receptor binding step. Three other mutants encoded virion-associated envelope proteins that could not confer resistance to superinfection, implying that they could not bind to the receptor. These mutants demonstrate that in M-MuLV, receptor binding and early events such as membrane fusion can be affected by amino acid changes in the TM protein.
Insights
Moloney murine leukemia virus (M-MuLV) envelope protein mutants were studied to understand viral replication. Amino acid changes in the TM protein affect M-MuLV
Area of Science:
- Virology
- Molecular Biology
- Cellular Biology
Background:
- Retroviral envelope proteins are crucial for viral entry, mediating receptor binding and membrane fusion.
- The TM protein (p15E) of Moloney murine leukemia virus (M-MuLV) plays a key role in these early infection steps.
Purpose of the Study:
- To investigate the function of the M-MuLV TM protein by generating and analyzing point mutants.
- To identify specific roles of TM protein domains in viral replication, receptor binding, and membrane fusion.
Main Methods:
- Generation of 21 point mutants in the M-MuLV TM protein (p15E).
- Assessment of mutant infectivity, virion-associated envelope protein levels, and ability to confer resistance to superinfection.
Main Results:
- One mutant showed a specific defect in a post-receptor binding step.
- Three mutants exhibited defects in receptor binding, indicated by their inability to confer resistance to superinfection.
- These findings highlight the TM protein's importance in M-MuLV's early infection stages.
Conclusions:
- Amino acid alterations in the M-MuLV TM protein can significantly impact viral receptor binding and membrane fusion.
- The TM protein is essential for multiple stages of retroviral infection, from initial binding to membrane fusion.