Viruses are among the ultimate conquerors. Even the exploits of Genghis Khan and Alexander the Great seem pale when compared to viral feats. To give but one example, over the last 50 years, the human immunodeficiency virus (HIV) has swept across six continents, now claiming several million lives yearly. Despite sustained intense research efforts, there is still no treatment to eradicate HIV infection. / For billions of years, viruses evolved strategies to enter and take control of organisms to generate progeny viruses. Eukaryotic cell viruses developed various means of hijacking the cellular protein synthesis machinery. Understanding these mechanisms opens a unique window of opportunity: that of eventually being able to specifically inhibit virus protein production. In this context, we investigated how HIV-1 translation is regulated. This work initially characterizes an RNA structural element in the HIV-1 leader able to directly recruit the protein synthesis machinery, i.e. an internal ribosome entry site (IRES). This element is capable of driving protein synthesis during the G2/M cell-cycle phase when cap-dependent translation is inhibited. / Several virus families use IRESs. IRES-dependent translation usually involves a subset of the factors implicated in cellular protein synthesis. However, toeprinting studies suggest that HIV-1 requires factors different from the canonical translation initiation factors to initiate protein synthesis. HeLa cell protein fractionation studies identified p97, an eIF4G homolog, its apoptotic cleavage product, p86, and a novel protein, ropp120, as putative HIV-1 transactivators. Further testing revealed that these proteins do not directly stimulate HIV-1 leader dependent translation. Experiments also showed that La autoantigen, another likely HIV-1 IRES transactivator candidate, does not directly stimulate HIV-1 dependent translation. / The last portion of this work investigates the interplay of the HIV-1 IRES with cap structures, polyA tails and the HIV-1 3'UTR region since these elements are present on the viral genomic RNA. We found that the HIV-1 leader does not synergize nor does it interfere with the translation stimulation mediated by the cap, the polyA and the HIV-1 3'UTR. Data presented herein suggest that the HIV-1 leader is an IRES able to shunt initiation complexes from the cap structure to drive protein synthesis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85890 |
| Date | January 2005 |
| Creators | Brasey, Ann |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biochemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002260921, proquestno: AAINR21627, Theses scanned by UMI/ProQuest. |
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