Cargando…
A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction
BACKGROUND: The HIV-1 accessory proteins, Viral Infectivity Factor (Vif) and the pleiotropic Viral Protein R (Vpr) are important for efficient virus replication. While in non-permissive cells an appropriate amount of Vif is critical to counteract APOBEC3G-mediated host restriction, the Vpr-induced G...
Autores principales: | , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2014
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163160/ https://www.ncbi.nlm.nih.gov/pubmed/25169827 http://dx.doi.org/10.1186/s12977-014-0072-1 |
_version_ | 1782334750478827520 |
---|---|
author | Widera, Marek Hillebrand, Frank Erkelenz, Steffen Vasudevan, Ananda Ayyappan Jaguva Münk, Carsten Schaal, Heiner |
author_facet | Widera, Marek Hillebrand, Frank Erkelenz, Steffen Vasudevan, Ananda Ayyappan Jaguva Münk, Carsten Schaal, Heiner |
author_sort | Widera, Marek |
collection | PubMed |
description | BACKGROUND: The HIV-1 accessory proteins, Viral Infectivity Factor (Vif) and the pleiotropic Viral Protein R (Vpr) are important for efficient virus replication. While in non-permissive cells an appropriate amount of Vif is critical to counteract APOBEC3G-mediated host restriction, the Vpr-induced G2 arrest sets the stage for highest transcriptional activity of the HIV-1 long terminal repeat. Both vif and vpr mRNAs harbor their translational start codons within the intron bordering the non-coding leader exons 2 and 3, respectively. Intron retention relies on functional cross-exon interactions between splice sites A1 and D2 (for vif mRNA) and A2 and D3 (for vpr mRNA). More precisely, prior to the catalytic step of splicing, which would lead to inclusion of the non-coding leader exons, binding of U1 snRNP to the 5' splice site (5'ss) facilitates recognition of the 3'ss by U2 snRNP and also supports formation of vif and vpr mRNA. RESULTS: We identified a G run localized deep in the vpr AUG containing intron 3 (G(I3)-2), which was critical for balanced splicing of both vif and vpr non-coding leader exons. Inactivation of G(I3)-2 resulted in excessive exon 3 splicing as well as exon-definition mediated vpr mRNA formation. However, in an apparently mutually exclusive manner this was incompatible with recognition of upstream exon 2 and vif mRNA processing. As a consequence, inactivation of G(I3)-2 led to accumulation of Vpr protein with a concomitant reduction in Vif protein. We further demonstrate that preventing hnRNP binding to intron 3 by G(I3)-2 mutation diminished levels of vif mRNA. In APOBEC3G-expressing but not in APOBEC3G-deficient T cell lines, mutation of G(I3)-2 led to a considerable replication defect. Moreover, in HIV-1 isolates carrying an inactivating mutation in G(I3)-2, we identified an adjacent G-rich sequence (G(I3)-1), which was able to substitute for the inactivated G(I3)-2. CONCLUSIONS: The functionally conserved intronic G run in HIV-1 intron 3 plays a major role in the apparently mutually exclusive exon selection of vif and vpr leader exons and hence in vif and vpr mRNA formation. The competition between these exons determines the ability to evade APOBEC3G-mediated antiviral effects due to optimal vif expression. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12977-014-0072-1) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-4163160 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-41631602014-09-15 A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction Widera, Marek Hillebrand, Frank Erkelenz, Steffen Vasudevan, Ananda Ayyappan Jaguva Münk, Carsten Schaal, Heiner Retrovirology Research BACKGROUND: The HIV-1 accessory proteins, Viral Infectivity Factor (Vif) and the pleiotropic Viral Protein R (Vpr) are important for efficient virus replication. While in non-permissive cells an appropriate amount of Vif is critical to counteract APOBEC3G-mediated host restriction, the Vpr-induced G2 arrest sets the stage for highest transcriptional activity of the HIV-1 long terminal repeat. Both vif and vpr mRNAs harbor their translational start codons within the intron bordering the non-coding leader exons 2 and 3, respectively. Intron retention relies on functional cross-exon interactions between splice sites A1 and D2 (for vif mRNA) and A2 and D3 (for vpr mRNA). More precisely, prior to the catalytic step of splicing, which would lead to inclusion of the non-coding leader exons, binding of U1 snRNP to the 5' splice site (5'ss) facilitates recognition of the 3'ss by U2 snRNP and also supports formation of vif and vpr mRNA. RESULTS: We identified a G run localized deep in the vpr AUG containing intron 3 (G(I3)-2), which was critical for balanced splicing of both vif and vpr non-coding leader exons. Inactivation of G(I3)-2 resulted in excessive exon 3 splicing as well as exon-definition mediated vpr mRNA formation. However, in an apparently mutually exclusive manner this was incompatible with recognition of upstream exon 2 and vif mRNA processing. As a consequence, inactivation of G(I3)-2 led to accumulation of Vpr protein with a concomitant reduction in Vif protein. We further demonstrate that preventing hnRNP binding to intron 3 by G(I3)-2 mutation diminished levels of vif mRNA. In APOBEC3G-expressing but not in APOBEC3G-deficient T cell lines, mutation of G(I3)-2 led to a considerable replication defect. Moreover, in HIV-1 isolates carrying an inactivating mutation in G(I3)-2, we identified an adjacent G-rich sequence (G(I3)-1), which was able to substitute for the inactivated G(I3)-2. CONCLUSIONS: The functionally conserved intronic G run in HIV-1 intron 3 plays a major role in the apparently mutually exclusive exon selection of vif and vpr leader exons and hence in vif and vpr mRNA formation. The competition between these exons determines the ability to evade APOBEC3G-mediated antiviral effects due to optimal vif expression. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12977-014-0072-1) contains supplementary material, which is available to authorized users. BioMed Central 2014-08-29 /pmc/articles/PMC4163160/ /pubmed/25169827 http://dx.doi.org/10.1186/s12977-014-0072-1 Text en © Widera et al.; licensee BioMed Central Ltd. 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Widera, Marek Hillebrand, Frank Erkelenz, Steffen Vasudevan, Ananda Ayyappan Jaguva Münk, Carsten Schaal, Heiner A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction |
title | A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction |
title_full | A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction |
title_fullStr | A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction |
title_full_unstemmed | A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction |
title_short | A functional conserved intronic G run in HIV-1 intron 3 is critical to counteract APOBEC3G-mediated host restriction |
title_sort | functional conserved intronic g run in hiv-1 intron 3 is critical to counteract apobec3g-mediated host restriction |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163160/ https://www.ncbi.nlm.nih.gov/pubmed/25169827 http://dx.doi.org/10.1186/s12977-014-0072-1 |
work_keys_str_mv | AT wideramarek afunctionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT hillebrandfrank afunctionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT erkelenzsteffen afunctionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT vasudevananandaayyappanjaguva afunctionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT munkcarsten afunctionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT schaalheiner afunctionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT wideramarek functionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT hillebrandfrank functionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT erkelenzsteffen functionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT vasudevananandaayyappanjaguva functionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT munkcarsten functionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction AT schaalheiner functionalconservedintronicgruninhiv1intron3iscriticaltocounteractapobec3gmediatedhostrestriction |