title: Mapping of multiple RNA binding sites of human T-cell lymphotropic virus type I rex protein within 5'- and 3'-Rex response elements.
abstract: Interaction between the human T-cell lymphotropic virus type I Rex protein and viral transcripts in the nucleus is essential to the cytoplasmic appearance of unspliced and singly spliced viral RNA. Rex has been shown to mediate its function through direct interaction with a highly ordered secondary structure in the 3'-untranslated region of all human T-cell lymphotropic virus type I mRNAs termed the Rex response element (3'-RxRE). Part of the 3'-RxRE sequence is also present in the 5'-end of viral transcripts (5'-RxRE), and we demonstrate that Rex binds to this RNA with essentially the same affinity and specificity as to the 3'-RxRE. We have analyzed the secondary structures and binding sites of Rex within the 5'- and 3'-RxREs by enzymatic probing and chemical modification interference and show that multiple Rex molecules bind within a stem-loop, which is similarly structured in the two RxREs. Our experiments confirm the presence of a previously characterized Rex binding site but also identify a common motif within an extended region that comprises an additional Rex binding site. This suggests that Rex oligomerizes on the RxREs similarly to what has been observed for binding of the human immunodeficiency virus type 1 Rev protein to the Rev response element.
authors.affiliation: Department of Molecular and Structural Biology, University of Aarhus, C. F. Mollers Allé, Building 130, DK-8000 Aarhus C, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Askjaer
authors.forename: J
authors.initials: J
authors.lastname: Kjems
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002474:Cell-Free System; D015967:Gene Expression Regulation, Viral; D016370:Gene Products, rex / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D016370:Gene Products, rex; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins