Keywords :
Activating Transcription Factor 4; Amino Acid Sequence; Animals; Basic-Leucine Zipper Transcription Factors; COS Cells; DNA-Binding Proteins/chemistry/genetics; Down-Regulation; G-Box Binding Factors; Gene Expression Regulation, Viral; Human T-lymphotropic virus 1/genetics; Molecular Sequence Data; RNA, Complementary/genetics; RNA, Viral/genetics; Transcription Factors/chemistry/genetics/metabolism; Transcription, Genetic
Abstract :
[en] 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.
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