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Analysis and function of prototype foamy virus envelope N glycosylation
Daniel Lüftenegger1, Marcus Picard-Maureau, Nicole Stanke
1Institut für Virologie, Medizinische Fakultät "Carl Gustav Carus," Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany.
Journal of Virology
|May 28, 2005
Summary
Prototype foamy virus (PFV) glycoprotein N-glycosylation is crucial for particle release. Specific conserved sites on surface (SU) and transmembrane (TM) subunits are vital for PFV replication and infectivity.
Area of Science:
- Virology
- Glycobiology
- Molecular Biology
Background:
- Prototype foamy virus (PFV) glycoprotein undergoes complex posttranslational cleavage into leader peptide (LP), surface (SU), and transmembrane (TM) subunits.
- N-linked glycosylation is present on all PFV glycoprotein subunits, with varying oligosaccharide types (high-mannose, hybrid, complex).
Purpose of the Study:
- To investigate the role of N-glycosylation sites in PFV Env biosynthesis, particle release, and infectivity.
- To identify specific N-glycosylation sites critical for PFV Env function.
Main Methods:
- Metabolic labeling and glycosidase digestion of PFV particles.
- Site-directed mutagenesis of 15 potential N-glycosylation sites in PFV Env.
- Analysis of mutant glycoproteins for defects in processing, particle release, and infectivity.
Main Results:
- 14 out of 15 potential N-glycosylation sites are utilized in PFV Env (1 in LP, 10 in SU, 3 in TM).
- Inactivation of conserved sites N8 (SU) and N13 (TM) caused defects in intracellular processing, particle release, and infectivity.
- Mutations at N15 (TM) and surrounding sequences resulted in a temperature-sensitive phenotype, suggesting sequence contribution.
Conclusions:
- PFV Env, particularly the SU subunit, is extensively N-glycosylated.
- While most N-glycosylation sites are individually dispensable, conserved sites like N8 and N13 are essential for normal PFV Env function and viral replication across species.