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TTF‐I determines the chromatin architecture of the active rDNA promoter
Author(s) -
Längst Gernot,
Becker Peter B.,
Grummt Ingrid
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.11.3135
Subject(s) - german , biology , library science , philosophy , computer science , linguistics
Transcription of ribosomal genes assembled into chromatin requires binding of the transcription termination factor TTF‐I to the promoter‐proximal terminator T 0 . To analyze the mechanism of TTF‐I‐mediated transcriptional activation, we have used mutant templates with altered sequence, polarity and distance of T 0 with respect to the transcription start site. Transcription activation by TTF‐I is chromatin specific and requires the precise positioning of the terminator relative to the promoter. Whereas termination by TTF‐I depends on the correct orientation of a terminator, TTF‐I‐mediated transcriptional activation is orientation independent. TTF‐I can bind to nucleosomal DNA in the absence of enzymatic activities that destabilize nucleosome structure. Chromatin‐bound TTF‐I synergizes with ATP‐dependent cofactors present in extracts of Drosophila embryos and mouse cells to position a nucleosome over the rDNA promoter and the transcription start site. Nucleosome positioning correlates tightly with the activation of rDNA transcription. We suggest that transcriptional activation by TTF‐I is a stepwise process involving the creation of a defined promoter architecture and that the positioning of a nucleosome is compatible with, if not a prerequisite for, transcription initiation from rDNA chromatin.