Open AccessRequirement of multiple copies of a 21-nucleotide sequence in the U3 regions of human T-cell leukemia virus type I and type II long terminal repeats for trans-acting activation of transcription.
Author(s) -
Kunitada Shimotohno,
Masako Takano,
Toshiyuki Teruuchi,
Miwa Misawa
Publication year - 1986
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.83.21.8112
Subject(s) - long terminal repeat , biology , chloramphenicol acetyltransferase , microbiology and biotechnology , nucleic acid sequence , enhancer , genetics , murine leukemia virus , direct repeat , inverted repeat , nucleotide , virology , gene , transcription factor , reporter gene , genome , gene expression
The cis-acting regulatory sequence of transcription from long terminal repeats (LTRs) of human T-cell leukemia virus type I and type II (HTLV-I and HTLV-II), which is essential for action of the virally encoded trans-acting transcriptional factor(s) designated pX(s), in HTLV-I and -II was identified. Deletion of most of the U3 region of the HTLV-I LTR resulted in loss of trans-acting transcriptional activation. However, when a tandem repeat of a 21-nucleotide sequence (GAAGGCTCTGACGTCT) that is present in the U3 region of HTLV-I and -II LTRs was inserted into the deleted U3 region of the HTLV-I LTRs, chloramphenicol acetyltransferase activity was restored. The extent of restoration of activity was proportional to the number of copies of the sequence inserted. To test the possibility that the 21-nucleotide sequence alone is necessary for trans-activation, a sequence (AGGAACTGAAA) homologous to a type-specific viral enhancer sequence and present in the U3 region of HTLV-II LTR, but not in the same region of the HTLV-I LTR, was inserted together with the 21-nucleotide sequence into the deleted U3 region of the HTLV-I LTR. However, no significant differences of the levels of activities of those LTRs compared to the LTRs with only the 21-nucleotide sequence repeats were observed.