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J Virol. 2009 Jul;83(14):7210-20. doi: 10.1128/JVI.02603-08. Epub 2009 Apr 29.

Uncoupling human immunodeficiency virus type 1 Gag and Pol reading frames: role of the transframe protein p6* in viral replication.

Author information

1
Molecular Microbiology and Gene Therapy Unit, Institute of Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany.

Abstract

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.

PMID:
19403679
PMCID:
PMC2704792
DOI:
10.1128/JVI.02603-08
[Indexed for MEDLINE]
Free PMC Article

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