Structural requirement for the two-step dimerization of human immunodeficiency virus type 1 genome

• Published in: RNA (Cambridge) Vol. 6; no. 1; pp. 96 - 102
• Main Authors: TAKAHASHI, KEN-ICHI, BABA, SEIKI, CHATTOPADHYAY, PRATIMA, KOYANAGI, YOSHIO, YAMAMOTO, NAOKI, TAKAKU, HIROSHI, KAWAI, GOTA
• Format: Journal Article
• Language: English
• Published: United States Cambridge University Press 01-01-2000
• Subjects: AIDS/HIV; Capsid - metabolism; Capsid Proteins; Dimerization; Electrophoresis, Polyacrylamide Gel; gag Gene Products, Human Immunodeficiency Virus; Gene Products, gag - metabolism; Genome, Viral; HIV-1 - chemistry; HIV-1 - genetics; Human immunodeficiency virus 1; Magnesium - pharmacology; Nucleic Acid Conformation; RNA, Viral - chemistry; RNA, Viral - metabolism; Viral Proteins; HIV-1; RNA; NCp7; nucleocapsid protein; electrophoresis; DIS; kissing-loop
• ISSN: 1355-8382; 1469-9001
• DOI: 10.1017/S1355838200991635

Generation of RNA dimeric form of the human immunodeficiency
virus type 1 (HIV-1) genome is crucial for viral replication.
The dimerization initiation site (DIS) has been identified
as a primary sequence that can form a stem-loop structure
with a self-complementary sequence in the loop and a bulge
in the stem. It has been reported that HIV-1 RNA fragments
containing the DIS form two types of dimers, loose dimers
and tight dimers. The loose dimers are spontaneously generated
at the physiological temperature and converted into tight
dimers by the addition of nucleocapsid protein NCp7. To
know the biochemical process in this two-step dimerization
reaction, we chemically synthesized a 39-mer RNA covering
the entire DIS sequence and also a 23-mer RNA covering
the self-complementary loop and its flanking stem within
the DIS. Electrophoretic dimerization assays demonstrated
that the 39-mer RNA reproduced the two-step dimerization
process, whereas the 23-mer RNA immediately formed the
tight dimer. Furthermore, deletion of the bulge from the
39-mer RNA prevented the NCp7-assisted tight-dimer formation.
Therefore, the whole DIS sequence is necessary and sufficient
for the two-step dimerization. Our data suggested that
the bulge region regulates the stability of the stem and
guides the DIS to the two-step dimerization process.