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Mol. Cell. Biol., 01 1998, 10-18, Vol 18, No. 1
K Ikeda, JP Halle, G Stelzer, M Meisterernst and K Kawakami
The transcription factor AREB6 contains a homeodomain flanked by two
clusters of Kruppel type C2H2 zinc fingers. AREB6 binds to the E-box
consensus sequence, CACCTGT, through either the N- or the C-terminal zinc
finger cluster. To gain insights into the molecular mechanism by which
AREB6 activates and represses gene expression, we analyzed the domain
structure of AREB6 in the context of a heterologous DNA-binding domain by
transient-transfection assays. The C-terminal region spanning amino acids
1011 to 1124 was identified as a conventional acidic activation domain. The
region containing amino acids 754 to 901, which was identified as a
repression domain, consists of 40% hydrophobic amino acids displaying no
sequence similarities to other known repression domains. This region
repressed transcription in vitro in a HeLa nuclear extract but not in
reconstituted transcription systems consisting of transcription factor IID
(TFIID), TFIIB, TFIIE, TFIIH/F, and RNA polymerase II. The addition of
recombinant negative cofactor NC2 (NC2alpha/DRAP1 and NC2beta/Dr1) to the
reconstituted transcription system restored the activity of the AREB6
repression domain. We further demonstrated interactions between the AREB6
repression domain and NC2alpha in yeast two-hybrid assay. Our findings
suggest a mechanism of transcriptional repression that is mediated by the
general cofactor NC2.
Copyright © 1998, American Society for Microbiology
Involvement of negative cofactor NC2 in active repression by zinc finger-homeodomain transcription factor AREB6
Department of Biology, Jichi Medical School, Kawachi, Tochigi, Japan.
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