THE MULTIMERIZATION STATE OF RETROVIRAL RNA IS MODULATED BY AMMONIUM-IONS AND AFFECTS HIV-1 FULL-LENGTH CDNA SYNTHESIS IN-VITRO

Genomic human immunodeficiency virus type 1 (HIV-1) RNA fragments cont aining the dimer linkage structure (DLS) can be dimerized and multimer ized in the presence of NH4+ and in the absence of any other cation an d any viral or cellular protein. This effect strongly supports the not ion that dimerization and multimerization of genomic RNA occurs via pu rine-quartet formation in quadruple helical RNA structures. The effici ency of RNA dimerization and multimerization in the presence of ammoni um ions is about 400 fold increased as compared to alkali metal ions s uch as potassium. Dimerized retroviral RNA representing a pseudodiploi d genome could account for genetic recombination within the virion and during reverse transcription. Application of a novel South-Northern-B lotting procedure with biotinylated RNA and digoxigenin-labelled cDNA in vitro reveals that efficient human- and bovine tRNALys3 primed full -length cDNA-synthesis only takes place with a predominantly monomeriz ed RNA template. Dimerization and multimerization of the RNA significa ntly reduces full-length cDNA-synthesis. This suggests that monomeriza tion of the dimerized RNA, effected by delonization in vitro, is essen tial for efficient retroviral reverse transcription in vivo.