Overexpression of the HIV-1 Gag-Pol Polyprotein Results in Intracellular Activation of HIV-1 Protease and Inhibition of Assembly and Budding of Virus-like Particles

Karacostas, Velissarios; Wolffe, Elizabeth J.; Nagashima, Kunio; Gonda, Matthew A.; Moss, Bernard

doi:10.1006/viro.1993.1174

Cited by 197 publications

(155 citation statements)

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“…The production of Gag-Pol is likely important for packaging the Pol products within the particle. Furthermore, the level of Pol relative to Gag is critical for retroelement viability because particle assembly requires many more copies of Gag than Pol (Park and Morrow 1991;Karacostas et al 1993;Shehu-Xhilaga et al 2001;Telenti et al 2002), and therefore Pol is typically expressed at the translational level through deviations from standard decoding mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Translational recoding signals between gag and pol in diverse LTR retrotransposons

Gao

Havecker

Baranov

et al. 2003

RNA

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Because of their compact genomes, retroelements (including retrotransposons and retroviruses) employ a variety of translational recoding mechanisms to express Gag and Pol. To assess the diversity of recoding strategies, we surveyed gag/pol gene organization among retroelements from diverse host species, including elements exhaustively recovered from the genome sequences of Caenorhabditis elegans, Drosophila melanogaster, Schizosaccharomyces pombe, Candida albicans, and Arabidopsis thaliana. In contrast to the retroviruses, which typically encode pol in the −1 frame relative to gag, nearly half of the retroelements surveyed encode a single gag-pol open reading frame. This was particularly true for the Ty1/copia group retroelements. Most animal Ty3/gypsy retroelements, on the other hand, encode gag and pol in separate reading frames, and likely express Pol through +1 or −1 frameshifting. Conserved sequences conforming to slippery sites that specify viral ribosomal frameshifting were identified among retroelements with pol in the −1 frame. None of the plant retroelements encoded pol in the −1 frame relative to gag; however, two closely related plant Ty3/gypsy elements encode pol in the +1 frame. Interestingly, a group of plant Ty1/copia retroelements encode pol either in a +1 frame relative to gag or in two nonoverlapping reading frames. These retroelements have a conserved stem-loop at the end of gag, and likely express pol either by a novel means of internal ribosomal entry or by a bypass mechanism.

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Section: Introductionmentioning

confidence: 99%

Translational recoding signals between gag and pol in diverse LTR retrotransposons

Gao

Havecker

Baranov

et al. 2003

RNA

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“…The Gag-Pol to Gag ratio in HIV-1 is critical for the RNA dimerization, particle assembly, replication, and viral infectivity (Park and Morrow 1991;Karacostas et al 1993;Shehu-Xhilaga et al 2001), which suggests that altering the frameshift efficiency could affect viral replication. So far, the frameshift efficiency has only been studied for subtype B of HIV-1 group M. However, the development of an antiviral strategy directed against frameshifting requires the characterization of the frameshift efficiency of the other subtypes.…”

Section: Introductionmentioning

confidence: 99%

Efficiency of a programmed −1 ribosomal frameshift in the different subtypes of the human immunodeficiency virus type 1 group M

Baril

Dulude²,

Gendron³

et al. 2003

RNA

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The synthesis of the Gag-Pol polyprotein, the precursor of the enzymes of the human immunodeficiency virus type 1 (HIV-1), requires a programmed −1 ribosomal frameshift. This frameshift has been investigated so far only for subtype B of HIV-1 group M. In this subtype, the frameshift stimulatory signal was found to be a two-stem helix, in which a three-purine bulge interrupts the two stems. In this study, using a luciferase reporter system, we compare, for the first time, the frameshift efficiency of all the subtypes of group M. Mutants of subtype B, including a natural variant were also investigated. Our results with mutants of subtype B confirm that the bulge and the lower stem of the frameshift stimulatory signal contribute to the frameshift in addition to the upper stem-loop considered previously as the sole participant. Our results also show that the frameshift stimulatory signal of all of the other subtypes of group M can be folded into the same structure as in subtype B, despite sequence variations. Moreover, the frameshift efficiency of these subtypes, when assessed in cultured cells, falls within a narrow window (the maximal deviation from the mean value calculated from the experimental values of all the subtypes being ∼35%), although the predicted thermodynamic stability of the frameshift stimulatory signal differs between the subtypes (from −17.2 kcal/mole to −26.2 kcal/mole). The fact that the frameshift efficiencies fall within a narrow range for all of the subtypes of HIV-1 group M stresses the potential of the frameshift event as an antiviral target.

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“…As the HIV-1 protease, which is flanked by the highly variable p6 pol at its N terminus and by the reverse transcriptase (RT) at its C terminus (10,11), is responsible for all cleavages in the Gag-Pol precursor, its dimerization and autocatalytic release from the Gag-Pol are critical steps in the viral life cycle (4,13,14). Earlier studies have shown that premature activation or partial inhibition of the protease leads to retarded viral maturation (15)(16)(17)(18). Hence understanding the exact sequence of protease maturation from the Gag-Pol precursor has gained importance in recent years because of its intrinsic importance in viral maturation and as a target for drugs against AIDS (19).…”

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confidence: 99%

Folding Regulates Autoprocessing of HIV-1 Protease Precursor

Chatterjee

Mridula

Mishra

et al. 2005

Journal of Biological Chemistry

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Autoprocessing of HIV-1 protease (PR) precursors is a crucial step in the generation of the mature protease. Very little is known regarding the molecular mechanism and regulation of this important process in the viral life cycle. In this context we report here the first and complete residue level investigations on the structural and folding characteristics of the 17-kDa precursor TFR-PR-C nn (161 residues) of HIV-1 protease. The precursor shows autoprocessing activity indicating that the solution has a certain population of the folded active dimer. Removal of the 5-residue extension, C nn at the C-terminal of PR enhanced the activity to some extent. However, NMR structural characterization of the precursor containing a mutation, D25N in the PR at pH 5.2 and 32°C under different conditions of partial and complete denaturation by urea, indicate that the precursor has a high tendency to be unfolded. The major population in the ensemble displays some weak folding propensities in both the TFR and the PR regions, and many of these in the PR region are the non-native type. As both D25N mutant and wild-type PR are known to fold efficiently to the same native dimeric form, we infer that TFR cleavage enables removal of the non-native type of preferences in the PR domain to cause constructive folding of the protein. These results indicate that intrinsic structural and folding preferences in the precursor would have important regulatory roles in the autoprocessing reaction and generation of the mature enzyme.

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Overexpression of the HIV-1 Gag-Pol Polyprotein Results in Intracellular Activation of HIV-1 Protease and Inhibition of Assembly and Budding of Virus-like Particles

Cited by 197 publications

References 0 publications

Translational recoding signals between gag and pol in diverse LTR retrotransposons

Translational recoding signals between gag and pol in diverse LTR retrotransposons

Efficiency of a programmed −1 ribosomal frameshift in the different subtypes of the human immunodeficiency virus type 1 group M

Folding Regulates Autoprocessing of HIV-1 Protease Precursor

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