title: In vitro binding of human T-cell leukemia virus rex proteins to the rex-response element of viral transcripts.
abstract: Human T-cell leukemia virus (HTLV-I, HTLV-II) rex protein function is required for the cytoplasmic expression of incompletely spliced viral transcripts encoding structural proteins. The effect is mediated by a cis-acting rex-response element (RRX) which is located near the 3' end of all viral mRNAs. We show that rex polypeptides of HTLV-I and HTLV-II expressed in Escherichia coli are capable of specifically binding RRX-containing transcripts of both viruses in cell-free assays. Binding analyses with deletion variants of rex proteins revealed a domain with RNA-binding activity in the first 77 N-terminal amino acids. Removal of a basic peptide of 19 amino acids from the N terminus abrogated RNA binding, whereas a beta-galactosidase fusion protein containing this peptide bound to the RRX. These results suggest that direct binding of rex protein to the RRX is important for rex-mediated regulation of viral gene expression and that a short stretch of positively charged amino acids contributes to the specific binding of rex to its target RNA.
authors.affiliation: Institut für Klinische und Molejulare Virologie, Universität Erlangen-Nürnberg, Federal Republic of Germany.
authors.forename: R
authors.initials: R
authors.lastname: Grassmann
authors.forename: S
authors.initials: S
authors.lastname: Berchtold
authors.forename: C
authors.initials: C
authors.lastname: Aepinus
authors.forename: C
authors.initials: C
authors.lastname: Ballaun
authors.forename: E
authors.initials: E
authors.lastname: Boehnlein
authors.forename: B
authors.initials: B
authors.lastname: Fleckenstein
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D015967:Gene Expression Regulation, Viral; D016370:Gene Products, rex / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D015367:Human T-lymphotropic virus 2 / Q000235:genetics; D012367:RNA, Viral / Q000378:metabolism*; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic
chemical_list: D002352:Carrier Proteins; D016370:Gene Products, rex; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins