Viral RNA binding properties of human immunodeficiency virus type-2 (HIV-2) nucleocapsid protein-derived synthetic...

The nucleocapsid (NC) protein of HIV-2 (NCp8) contains two Cys-His arrays which function as zinc finger motifs (ZFMs). In this study, we analyzed the viral RNA-binding properties of NCp8-derived synthetic peptides using ultraviolet (UV) cross-linking assay. Several synthetic peptides containing ZFM(s) interacted pH-dependently with in vitro-synthesized HIV-2 RNA. Although the peptides corresponding to the 1st and 2nd ZFMs, respectively, failed to interact with the viral RNA, the corresponding peptides flanked by basic amino acid clusters interacted tightly. Furthermore, basic amino acid residues within a cluster adjacent to ZFMs contributed to the RNA-binding of NCp8 more than Cys and His residues within the ZFM in vitro. In competitive UV cross-linking assay using non-specific RNA as a competitor, the peptides corresponding to the 1st and 2nd ZFMs flanked by basic amino acid clusters interacted specifically with viral RNA. These findings suggest that both ZFM regions of HIV-2 may be concerned with the specificity of packaging of genomic viral RNA into the virion.