A p6Pol-protease fusion protein is present in mature particles of human immunodeficiency virus type 1

Almog, Nava; Roller, Richard J.; Arad, Gila; Passi-Even, L.; Wainberg, Mark A.; Kotler, Moshe

doi:10.1128/jvi.70.10.7228-7232.1996

Cited by 22 publications

(17 citation statements)

References 31 publications

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“…Mutation of the N-terminal PR cleavage site in the context of a complete provirus led to formation of a p6*-PR fusion protein which is likely cleaved at the previously described site at the very beginning of the Pol sequence (2,20,30). This N-terminally extended PR is proteolytically active and cleaves the Pol domain quite efficiently.…”

mentioning

confidence: 85%

“…These sites include the sites of the known cleavages separating PR, RT, and integrase and also a site that separates the p6* domain of Pol from the Gag domain of the precursor protein. This site most likely corresponds to the sequence Asp Leu Ala Phe * Leu Gln Gly Lys (the asterisk denotes the scissile bond) in the N-terminal region of p6*, which has been shown previously to be a substrate for PR (2,20,30). Cleavage at this site generates an apparently stable extended PR species which is capable of cleaving all other sites in the Pol domain (albeit with reduced efficiency) but which yields only weak cleavage of the viral Gag polyprotein.…”

mentioning

confidence: 93%

“…This 11-kDa PR was detected in four different HIV-1 strains and in particles obtained from four different cell lines, with no evidence for a significant amount of an extended 17-kDa PR species. In a previous report, Almog et al (2) had observed a 17-kDa PR in HIV-1 particles (strains IIIb and MN) obtained from monocytic cell line U937 and suggested that p6*-PR may be the active form of PR inside the viral particles. This discrepancy may be due to a significant difference in polyprotein processing in U937 cell-derived HIV-1 particles or to the relative specificity of the antisera employed.…”

mentioning

confidence: 94%

“…Besides cleaving peptide substrates, miniprecursors contain-ing PR cleavage site mutants have also been shown to cleave additional sites within the p6* region leading to p6*-PR fusion proteins (2,20,30). Very recently, Almog et al (2) reported that the predominant PR species in mature HIV type 1 (HIV-1) particles is a 17-kDa protein containing the p6* and PR domains, which suggested that the 99-amino-acid PR observed in heterologous expression systems may not be the PR species active in viral replication. This observation is in contrast to previous reports which showed that N-terminal extensions of HIV PR caused a decrease in autocatalytic release of PR (15) and reduced activity towards polyprotein substrates in trans (30).…”

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confidence: 99%

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Cleavage of Human Immunodeficiency Virus Type 1 Proteinase from the N-Terminally Adjacent p6* Protein Is Essential for Efficient Gag Polyprotein Processing and Viral Infectivity

Tessmer

Kräusslich

1998

J Virol

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Maturation of infectious human immunodeficiency virus (HIV) particles requires proteolytic cleavage of the structural polyproteins by the viral proteinase (PR), which is itself encoded as part of the Gag-Pol polyprotein. Expression of truncated PR-containing sequences in heterologous systems has mostly led to the autocatalytic release of an 11-kDa species of PR which is capable of processing all known cleavage sites on the viral precursor proteins. Relatively little is known about cleavages within the nascent virus particle, on the other hand, and controversial results concerning the active PR species inside the virion and the relative activities of extended PR species have been reported. Here, we report that HIV type 1 (HIV-1) particles of four different strains obtained from different cell lines contain an 11-kDa PR, with no extended PR proteins detectable. Furthermore, mutation of the N-terminal PR cleavage site leading to production of an N-terminally extended 17-kDa PR species caused a severe defect in Gag polyprotein processing and a complete loss of viral infectivity. We conclude that N-terminal release of PR from the HIV-1 polyprotein is essential for viral replication and suggest that extended versions of PR may have a transient function in the proteolytic cascade.

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confidence: 85%

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confidence: 93%

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confidence: 94%

mentioning

confidence: 99%

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Cleavage of Human Immunodeficiency Virus Type 1 Proteinase from the N-Terminally Adjacent p6* Protein Is Essential for Efficient Gag Polyprotein Processing and Viral Infectivity

Tessmer

Kräusslich

1998

J Virol

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“…Cleavage of the viral polyproteins is a key step in viral maturation, and without specific cleavage of the precursors, the virion is not infectious 10–12. Previous studies have indicated that PR is already active in its Gag‐Pol precursor form, and that the cleavage of the polyproteins may occur by inter‐ or intramolecular mechanisms 13–15. HIV PR inhibitors are effective against wild‐type HIV both in vitro and in vivo, but are also rapidly selected for HIV variants displaying reduced susceptibility to the PR inhibitors 16.…”

Section: Introductionmentioning

confidence: 99%

Electronic Transduction of HIV‐1 Drug Resistance in AIDS Patients

Alfonta

Blumenzweig²,

Zayats

et al. 2004

ChemBioChem

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A drug composition consisting of nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs) is commonly used in AIDS therapy. A major difficulty encountered with the therapeutic composite involves the emergence of drug-resistant viruses, especially to the PIs, regarded as the most effective drugs in the composition. We present a novel bioelectronic means to detect the appearance of mutated HIV-1 exhibiting drug resistance to the PI saquinavir. The method is based on the translation of viral RNA, the association of cleaved or uncleaved Gag polyproteins at an electrode surface functionalized with the respective antibodies, and the bioelectronic detection of the Gag polyproteins associated with the surface. The bioelectronic process includes the association of anti-MA or anti-CA antibodies, the secondary binding of an antibody-horseradish peroxidase (HRP) conjugate, and the biocatalyzed precipitation of an insoluble product on the electronic transducers. Faradaic impedance measurements and quartz crystal microbalance analyses are employed to follow the autoprocessing of the Gag polyproteins. The method was applied to determine drug resistance in infected cultured cells and also in blood samples of consenting AIDS patients. The method described here is also applicable to the determination of drug effectiveness in AIDS patients and to screening of the efficiency of newly developed drugs.

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