Importance of Protease Cleavage Sites within and Flanking Human Immunodeficiency Virus Type 1 Transframe Protein p6* for Spatiotemporal Regulation of Protease Activation

Ludwig, Christine; Leiherer, Andreas; Wagner, Ralf

doi:10.1128/jvi.02353-07

Cited by 40 publications

(55 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interestingly, the autoprocessing of a truncated Gag-PR precursor was clearly accelerated when the p6* sequence was deleted, leading to the proposal that the active site of the PR might be less accessible in the presence of p6* (26). Further observations that p6* itself is sequentially cleaved by the PR (1,7,22,23,24,30,31,32,41) strengthened the hypothesis that the transframe protein contributes to spatiotemporal activation of the PR. Indeed, we and others have previously shown that the PR needs to be released from the flanking p6* residues to be capable of completing all virusassociated processing steps (24,27,36).…”

mentioning

confidence: 60%

“…Further observations that p6* itself is sequentially cleaved by the PR (1,7,22,23,24,30,31,32,41) strengthened the hypothesis that the transframe protein contributes to spatiotemporal activation of the PR. Indeed, we and others have previously shown that the PR needs to be released from the flanking p6* residues to be capable of completing all virusassociated processing steps (24,27,36). The potential of p6* to regulate PR activity has been further corroborated by our finding that recombinant p6* protein comprising a free accessible carboxyl terminus is a potent inhibitor of the mature PR in vitro (28).…”

mentioning

confidence: 65%

“…For analysis of virus production and infection experiments, 5 ϫ 10 6 293T cells were transiently transfected with 20 g of the various provirus plasmids by using polyethylenimine (PolySciences, Inc.) according to the manufacturer's instructions. To inhibit the viral PR, Saquinavir (Roche Diagnostics) was added to the medium at 4 h posttransfection at a final concentration of 10 M. Virus-containing supernatants were collected after 48 or 72 h, filtered through a 0.45-m-pore-size filter, and quantified for total amounts of particle-associated capsid (CA) protein by enzyme-linked immunosorbent assay (ELISA) by using CA-specific antibodies from Polymun (Vienna, Austria) as recently described in detail (24).…”

Section: Vol 83 2009mentioning

confidence: 99%

“…This complex sequence context imposes major restrictions on mutational analysis of the p6* amino terminus in the viral background (24). To allow for a more in-depth functional analysis of the conserved p6* residues in the viral context, we have established a novel NL4-3-based provirus with p1-p6 gag and p6* reading frames uncoupled via a dislocated frameshift site.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Uncoupling Human Immunodeficiency Virus Type 1 gag and pol Reading Frames: Role of the Transframe Protein p6* in Viral Replication

Leiherer

Ludwig

Wagner

2009

J Virol

Self Cite

View full text Add to dashboard Cite

Apart from its regulatory role in protease (PR) activation, little is known about the function of the human immunodeficiency virus type 1 transframe protein p6* in the virus life cycle. p6* is located between the nucleocapsid and PR domains in the Gag-Pol polyprotein precursor and is cleaved by PR during viral maturation. We have recently reported that the central region of p6* can be extensively mutated without abolishing viral infectivity and replication in vitro. However, mutagenesis of the entire p6*-coding sequence in the proviral context is not feasible without affecting the superimposed frameshift signal or the overlapping p1-p6 gag sequences. To overcome these limitations, we created a novel NL4-3-derived provirus by displacing the original frameshift signal to the 3 end of the gag gene, thereby uncoupling the p6* gene sequence from the p1-p6 gag reading frame. The resulting virus (AL) proved to be replication competent in different cell cultures and thus represents an elegant tool for detailed analysis of p6* function. Hence, extensive deletions or substitutions were introduced into the p6* gene sequence of the AL provirus, and effects on particle release, protein processing, and viral infectivity were evaluated. Interestingly, neither the deletion of 63% of all p6* residues nor the partial substitution by a heterologous sequence affected virus growth and infectivity, suggesting that p6* is widely dispensable for viral in vitro replication. However, the insertion of a larger reporter sequence interfered with virus production and maturation, implying that the length or conformation of this spacer region might be critical for p6* function.

show abstract

mentioning

confidence: 60%

mentioning

confidence: 65%

Section: Vol 83 2009mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Uncoupling Human Immunodeficiency Virus Type 1 gag and pol Reading Frames: Role of the Transframe Protein p6* in Viral Replication

Leiherer

Ludwig

Wagner

2009

J Virol

Self Cite

View full text Add to dashboard Cite

show abstract

“…In line with this evidence, a complete deletion of p6* enhances protease-mediated proteolytic processing (511). (ii) Cleavages on incorrect p6* positions may significantly reduce the maturation of viral particles, highlighting the importance of accurate cleavages at p6* for protease activation (512). (iii) Although GagPol precursors lacking the p6* region could be incorporated into HIV-1 particles, p6* exerts negative regulation on protease dimerization, and it is indispensable for protease-mediated maturation (513).…”

Section: Protease-gag/gagpol Interactionmentioning

confidence: 51%

HIV Genome-Wide Protein Associations: a Review of 30 Years of Research

Clercq

2016

Microbiol Mol Biol Rev

View full text Add to dashboard Cite

SUMMARYThe HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.

show abstract

HIV Protease Inhibitor Resistance

Wensing

Fun

Nijhuis

2014

Handbook of Antimicrobial Resistance

View full text Add to dashboard Cite

HIV protease is pivotal in the viral replication cycle and directs the formation of mature infectious virus particles. The development of highly specific HIV protease inhibitors (PIs), based on thorough understanding of the structure of HIV protease and its substrate, serves as a prime example of structure-based drug design. The introduction of first-generation PIs marked the start of combination antiretroviral therapy. However, low bioavailability, high pill burden, and toxicity ultimately reduced adherence and limited long-term viral inhibition. Therapy failure was often associated with multiple protease inhibitor resistance mutations, both in the viral protease and its substrate (HIV gag protein), displaying a broad spectrum of resistance mechanisms. Unfortunately, selection of protease inhibitor resistance mutations often resulted in cross-resistance to other PIs.Therefore, second-generation approaches were imperative. Coadministration of a cytochrome P-450 3A4 inhibitor greatly improved the plasma concentration of PIs in the patient. A second advance was the development of PIs that were efficacious against first-generation PI-resistant HIV. Both approaches increased the number of protease mutations required by the virus to develop clinically relevant resistance, thereby raising the genetic barrier towards PI resistance. These improvements greatly contributed to the success of PI-based therapy.

show abstract

Importance of Protease Cleavage Sites within and Flanking Human Immunodeficiency Virus Type 1 Transframe Protein p6* for Spatiotemporal Regulation of Protease Activation

Cited by 40 publications

References 63 publications

Uncoupling Human Immunodeficiency Virus Type 1 gag and pol Reading Frames: Role of the Transframe Protein p6* in Viral Replication

Uncoupling Human Immunodeficiency Virus Type 1 gag and pol Reading Frames: Role of the Transframe Protein p6* in Viral Replication

HIV Genome-Wide Protein Associations: a Review of 30 Years of Research

HIV Protease Inhibitor Resistance

Contact Info

Product

Resources

About