The complementary strand of the human T-cell leukemia virus type 1 RNA genome encodes a bZIP transcription factor that down-regulates viral transcription.
The RNA genome of the human T-cell leukemia virus type 1 (HTLV-1) codes for proteins involved in infectivity, replication, and transformation. We report in this study the characterization of a novel viral protein encoded by the complementary strand of the HTLV-1 RNA genome. This protein, designated HBZ (for HTLV-1 bZIP factor), contains a N-terminal transcriptional activation domain and a leucine zipper motif in its C terminus. We show here that HBZ is able to interact with the bZIP transcription factor CREB-2 (also called ATF-4), known to activate the HTLV-1 transcription by recruiting the viral trans-activator Tax on the Tax-responsive elements (TxREs). However, we demonstrate that the HBZ/CREB-2 heterodimers are no more able to bind to the TxRE and cyclic AMP response element sites. Taking these findings together, the functional inactivation of CREB-2 by HBZ is suggested to contribute to regulation of the HTLV-1 transcription. Moreover, the characterization of a minus-strand gene protein encoded by HTLV-1 has never been reported until now.
Gaudray
Gilles
G
Laboratoire Infections Rétrovirales et Signalisation Cellulaire, CNRS/UM I UMR 5121, Institut de Biologie, 4 Boulevard Henri IV, 34060 Montpellier, France.
Gachon
Frederic
F
Basbous
Jihane
J
Biard-Piechaczyk
Martine
M
Devaux
Christian
C
Mesnard
Jean-Michel
JM
D051701:Activating Transcription Factor 4; D000595:Amino Acid Sequence; D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors; D019556:COS Cells; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics*; D015536:Down-Regulation; D051790:G-Box Binding Factors; D015967:Gene Expression Regulation, Viral; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D008969:Molecular Sequence Data; D018075:RNA, Complementary / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D018075:RNA, Complementary; D012367:RNA, Viral; D014157:Transcription Factors; D051701:Activating Transcription Factor 4