HIV-1 Protease and Reverse Transcriptase Control the Architecture of Their Nucleocapsid PartnerReportar como inadecuado




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The HIV-1 nucleocapsid is formed during protease PR-directed viral maturation, and is transformed into pre-integration complexes following reverse transcription in the cytoplasm of the infected cell. Here, we report a detailed transmission electron microscopy analysis of the impact of HIV-1 PR and reverse transcriptase RT on nucleocapsid plasticity, using in vitro reconstitutions. After binding to nucleic acids, NCp15, a proteolytic intermediate of nucleocapsid protein NC, was processed at its C-terminus by PR, yielding premature NC NCp9 followed by mature NC NCp7, through the consecutive removal of p6 and p1. This allowed NC co-aggregation with its single-stranded nucleic-acid substrate. Examination of these co-aggregates for the ability of RT to catalyse reverse transcription showed an effective synthesis of double-stranded DNA that, remarkably, escaped from the aggregates more efficiently with NCp7 than with NCp9. These data offer a compelling explanation for results from previous virological studies that focused on i Gag processing leading to nucleocapsid condensation, and ii the disappearance of NCp7 from the HIV-1 pre-integration complexes. We propose that HIV-1 PR and RT, by controlling the nucleocapsid architecture during the steps of condensation and dismantling, engage in a successive nucleoprotein-remodelling process that spatiotemporally coordinates the pre-integration steps of HIV-1. Finally we suggest that nucleoprotein remodelling mechanisms are common features developed by mobile genetic elements to ensure successful replication.



Autor: Gilles Mirambeau , Sébastien Lyonnais , Dominique Coulaud, Laurence Hameau, Sophie Lafosse, Josette Jeusset, Isabelle Borde, Mic

Fuente: http://plos.srce.hr/



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