A single stem-loop structure within the HTLV-1 Rex response element is sufficient to mediate Rex activity in vivo.
The human T-cell leukemia virus (HTLV-1) Rex protein is required for the cytoplasmic expression of the incompletely spliced transcripts that encode the viral structural proteins. This effect is mediated by a highly structured cis-acting RNA element of 254 nucleotides termed the Rex response element, or RexRE. Here we demonstrate that one of the four known RexRE stem-loop structures as well as a 43-nt segment derived from this element is sufficient to mediate Rex function in vivo. Upon duplication, this stem-loop is shown to function as efficiently as the full-length RexRE. In vitro RNA binding analyses with wildtype and mutagenized RNA show that this stem-loop contains a high affinity binding site for Rex that coincides with a predicted bulge structure in the central part of this stem-loop. These results indicate that a small region of the RexRE containing a high affinity binding site is sufficient to mediate Rex function and suggest that sequences outside of this binding site have no unique role in mediating Rex regulation.
Gröne
M
M
Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Germany.
Hoffmann
E
E
Berchtold
S
S
Cullen
B R
BR
Grassmann
R
R
D001483:Base Sequence; D002460:Cell Line; D016370:Gene Products, rex / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D016372:RNA, Antisense / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D012367:RNA, Viral / Q000737:chemistry* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000235:genetics*
D016370:Gene Products, rex; D016372:RNA, Antisense; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins