Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication
<p>Abstract</p> <p>Background</p> <p>Foamy viruses (FVs) unlike orthoretroviruses express Pol as a separate precursor protein and not as a Gag-Pol fusion protein. A unique packaging strategy, involving recognition of briding viral RNA by both Pol precursor and Gag as we...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2011-08-01
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| Series: | Retrovirology |
| Subjects: | |
| Online Access: | http://www.retrovirology.com/content/8/1/66 |
| _version_ | 1818499299721347072 |
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| author | Reh Juliane Wiek Constanze Swiersy Anka Zentgraf Hanswalter Lindemann Dirk |
| author_facet | Reh Juliane Wiek Constanze Swiersy Anka Zentgraf Hanswalter Lindemann Dirk |
| author_sort | Reh Juliane |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Foamy viruses (FVs) unlike orthoretroviruses express Pol as a separate precursor protein and not as a Gag-Pol fusion protein. A unique packaging strategy, involving recognition of briding viral RNA by both Pol precursor and Gag as well as potential Gag-Pol protein interactions, ensures Pol particle encapsidation.</p> <p>Results</p> <p>Several Prototype FV (PFV) Gag-Pol fusion protein constructs were generated to examine whether PFV replication is compatible with an orthoretroviral-like Pol expression. During their analysis, non-particle-associated secreted Pol precursor protein was discovered in extracellular wild type PFV particle preparations of different origin, copurifying in simple virion enrichment protocols. Different analysis methods suggest that extracellular wild type PFV particles contain predominantly mature p85<sup>PR-RT </sup>and p40<sup>IN </sup>Pol subunits. Characterization of various PFV Gag-Pol fusion constructs revealed that PFV Pol expression in an orthoretroviral manner is compatible with PFV replication as long as a proteolytic processing between Gag and Pol proteins is possible. PFV Gag-Pol translation by a HIV-1 like ribosomal frameshift signal resulted in production of replication-competent virions, although cell- and particle-associated Pol levels were reduced in comparison to wild type. In-frame fusion of PFV Gag and Pol ORFs led to increased cellular Pol levels, but particle incorporation was only marginally elevated. Unlike that reported for similar orthoretroviral constructs, a full-length in-frame PFV Gag-Pol fusion construct showed wildtype-like particle release and infectivity characteristics. In contrast, in-frame PFV Gag-Pol fusion with C-terminal Gag ORF truncations or non-removable Gag peptide addition to Pol displayed wildtype particle release, but reduced particle infectivity. PFV Gag-Pol precursor fusion proteins with inactivated protease were highly deficient in regular particle release, although coexpression of p71<sup>Gag </sup>resulted in a significant copackaging of these proteins.</p> <p>Conclusions</p> <p>Non-particle associated PFV Pol appears to be naturally released from infected cells by a yet unknown mechanism. The absence of particle-associated Pol precursor suggests its rapid processing upon particle incorporation. Analysis of different PFV Gag-Pol fusion constructs demonstrates that orthoretroviral-like Pol expression is compatible with FV replication in principal as long as fusion protein processing is possible. Furthermore, unlike orthoretroviruses, PFV particle release and infectivity tolerate larger differences in relative cellular Gag/Pol levels.</p> |
| first_indexed | 2024-12-10T20:27:30Z |
| format | Article |
| id | doaj.art-0974d887c5564642b3b2580428683781 |
| institution | Directory Open Access Journal |
| issn | 1742-4690 |
| language | English |
| last_indexed | 2024-12-10T20:27:30Z |
| publishDate | 2011-08-01 |
| publisher | BMC |
| record_format | Article |
| series | Retrovirology |
| spelling | doaj.art-0974d887c5564642b3b25804286837812022-12-22T01:34:48ZengBMCRetrovirology1742-46902011-08-01816610.1186/1742-4690-8-66Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replicationReh JulianeWiek ConstanzeSwiersy AnkaZentgraf HanswalterLindemann Dirk<p>Abstract</p> <p>Background</p> <p>Foamy viruses (FVs) unlike orthoretroviruses express Pol as a separate precursor protein and not as a Gag-Pol fusion protein. A unique packaging strategy, involving recognition of briding viral RNA by both Pol precursor and Gag as well as potential Gag-Pol protein interactions, ensures Pol particle encapsidation.</p> <p>Results</p> <p>Several Prototype FV (PFV) Gag-Pol fusion protein constructs were generated to examine whether PFV replication is compatible with an orthoretroviral-like Pol expression. During their analysis, non-particle-associated secreted Pol precursor protein was discovered in extracellular wild type PFV particle preparations of different origin, copurifying in simple virion enrichment protocols. Different analysis methods suggest that extracellular wild type PFV particles contain predominantly mature p85<sup>PR-RT </sup>and p40<sup>IN </sup>Pol subunits. Characterization of various PFV Gag-Pol fusion constructs revealed that PFV Pol expression in an orthoretroviral manner is compatible with PFV replication as long as a proteolytic processing between Gag and Pol proteins is possible. PFV Gag-Pol translation by a HIV-1 like ribosomal frameshift signal resulted in production of replication-competent virions, although cell- and particle-associated Pol levels were reduced in comparison to wild type. In-frame fusion of PFV Gag and Pol ORFs led to increased cellular Pol levels, but particle incorporation was only marginally elevated. Unlike that reported for similar orthoretroviral constructs, a full-length in-frame PFV Gag-Pol fusion construct showed wildtype-like particle release and infectivity characteristics. In contrast, in-frame PFV Gag-Pol fusion with C-terminal Gag ORF truncations or non-removable Gag peptide addition to Pol displayed wildtype particle release, but reduced particle infectivity. PFV Gag-Pol precursor fusion proteins with inactivated protease were highly deficient in regular particle release, although coexpression of p71<sup>Gag </sup>resulted in a significant copackaging of these proteins.</p> <p>Conclusions</p> <p>Non-particle associated PFV Pol appears to be naturally released from infected cells by a yet unknown mechanism. The absence of particle-associated Pol precursor suggests its rapid processing upon particle incorporation. Analysis of different PFV Gag-Pol fusion constructs demonstrates that orthoretroviral-like Pol expression is compatible with FV replication in principal as long as fusion protein processing is possible. Furthermore, unlike orthoretroviruses, PFV particle release and infectivity tolerate larger differences in relative cellular Gag/Pol levels.</p>http://www.retrovirology.com/content/8/1/66Foamy virusGag-Pol fusion proteinretroviral morphogenesiscapsid assemblyPol processing |
| spellingShingle | Reh Juliane Wiek Constanze Swiersy Anka Zentgraf Hanswalter Lindemann Dirk Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication Retrovirology Foamy virus Gag-Pol fusion protein retroviral morphogenesis capsid assembly Pol processing |
| title | Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication |
| title_full | Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication |
| title_fullStr | Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication |
| title_full_unstemmed | Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication |
| title_short | Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication |
| title_sort | orthoretroviral like prototype foamy virus gag pol expression is compatible with viral replication |
| topic | Foamy virus Gag-Pol fusion protein retroviral morphogenesis capsid assembly Pol processing |
| url | http://www.retrovirology.com/content/8/1/66 |
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