Plasma membrane targeting of chimeric intracisternal A-type particle polyproteins leads to particle release and specific activation of the viral proteinase
| Autor: | Alfred Janetzko, Reinhold Welker, Hans-Georg Kräusslich |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Polyproteins
Recombinant Fusion Proteins viruses Immunology Retroviridae Proteins Biology Microbiology Cell membrane Virology Endopeptidases medicine Extracellular Animals Virus Assembly Endoplasmic reticulum Cell Membrane Virion Proteins Group-specific antigen Molecular biology Cell biology Genes Intracisternal A-Particle Retroviridae medicine.anatomical_structure Cytoplasm Insect Science COS Cells Intracisternal A-Particle Intracellular Subcellular Fractions Research Article |
| Zdroj: | Journal of Virology. 71:5209-5217 |
| ISSN: | 1098-5514 0022-538X |
| DOI: | 10.1128/jvi.71.7.5209-5217.1997 |
| Popis: | Retrovirus morphogenesis involves assembly of structural Gag polyproteins with subsequent budding from the plasma membrane, followed by proteolytic cleavage by the viral proteinase (PR) and extracellular maturation to the infectious virion. Intracisternal A-type particles (IAPs) are defective retroviruses that assemble and bud at the membranes of the endoplasmic reticulum (ER), where they remain as immature particles consisting exclusively of uncleaved polyproteins. To analyze requirements for intracellular polyprotein transport and PR activation, we constructed deletion and substitution mutations in the IAP gag gene, including the putative ER-targeting signal. Mutant polyproteins were transported to various intracellular locations, including the nucleus, the cytoplasm, the ER, and the plasma membrane. Interestingly, assembly of capsid-like particle structures occurred at almost all sites. However, only those polyproteins transported to the plasma membrane were efficiently and specifically cleaved by viral PR, with cleavage occurring predominantly within the virus particle. Thus, at least in the experimental system presented here, retroviral particle assembly can occur at almost any location within the cell, while polyprotein processing and, consequently, virion maturation are confined to a specific cellular site. These results suggest that a factor restricted to the plasma membrane is required to trigger PR activation and maturation of infectious retroviruses. |
| Databáze: | OpenAIRE |
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