Unité de virologie humaine, Inserm-ENS 412, ENS 46, allée d'Italie, 69364 Lyon, France
The nucleocore of VIH, and of retroviruses, results from the tight association of the genomic RNA dimer with 2 500 molecules of a unique, basic protein referred to as the nucleocapsid protein (NCp) as well as molecules of the viral enzymes reverse transcriptase (RT) and integrase (IN). The genomic single stranded RNA is converted into a double stranded proviral DNA by RT in the nucleocore, a process which necessitates two strand transfers in order to generate a functional proviral DNA with long terminal repeats (LTR).
In this short review we have summarized the nucleic acids chaperoning functions of the nucleocapsid protein NCp7 of HIV1 implicated in the extent of proviral DNA synthesis by RT and in virus assembly and structure. The 3-D conformation of HIV1 NCp7 is characterized by a central globular domain, formed of two zinc fingers flanked by basic residues. The central globular domain of NCp appears to be critical to ensure complete proviral DNA synthesis by RT and for the formation of a correctly assembled virus core. The zinc finger domain of NC protein appears to be a well conserved feature amongst retroviruses and certain retrotransposons and this should facilitate rational approaches for the design of new antiviral drugs aimed at inhibiting the nucleic acids chaperoning functions of NC.