A single stem-loop structure within the HTLV-1 Rex response element is sufficient to mediate Rex activity in vivo

Virology. 1994 Oct;204(1):144-52. doi: 10.1006/viro.1994.1518.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cell Line
  • Gene Products, rex / metabolism*
  • Human T-lymphotropic virus 1 / genetics*
  • Human T-lymphotropic virus 1 / metabolism
  • Humans
  • Molecular Sequence Data
  • Mutagenesis
  • Nucleic Acid Conformation*
  • RNA, Antisense / metabolism
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism
  • RNA, Viral / chemistry*
  • RNA, Viral / metabolism
  • RNA-Binding Proteins / metabolism
  • Regulatory Sequences, Nucleic Acid*
  • Transcription, Genetic / genetics*


  • Gene Products, rex
  • RNA, Antisense
  • RNA, Messenger
  • RNA, Viral
  • RNA-Binding Proteins