HIV-1 NUCLEOCAPSID PROTEIN INDUCES MATURATION OF DIMERIC RETROVIRAL RNA IN-VITRO

After a retrovirus particle is released from the cell, the dimeric gen omic RNA undergoes a change in conformation, We have previously propos ed that this change, termed maturation of the dimer, is due to the act ion of nucleocapsid (NC) protein on the RNA within the virus particle. We now report that treatment of a 345-base synthetic fragment of Harv ey sarcoma virus RNA with recombinant or synthetic HIV-1 NC protein co nverts a less stable form of dimeric RNA to a more stable form, This p henomenon thus appears to reproduce the maturation of dimeric retrovir al RNA in a completely defined system in vitro. To our knowledge, matu ration of dimeric RNA within a retrovirus particle is the first exampl e of action of an ''RNA chaperone'' protein in vivo. Studies with muta nt NC proteins suggest that the activity depends upon basic amino acid residues flanking the N-terminal zinc finger and upon residues within the N-terminal finger, including an aromatic amino acid, but do not r equire the zinc finger structures themselves.