Transcription coactivator SAYP combines chromatin remodeler Brahma and transcription initiation factor TFIID into a single supercomplex

Abstract

Transcription activation by RNA polymerase II is a complicated process driven by combined, precisely coordinated action of a wide array of coactivator complexes, which carry out chromatin-directed activities and nucleate the assembly of the preinitiation complex on the promoter. Using various techniques, we have shown the existence of a stable coactivator supercomplex consisting of the chromatin-remodeling factor Brahma (SWI/SNF) and the transcription initiation factor TFIID, named BTFly (Brahma and TFIID in one assembly). The coupling of Brahma and TFIID is mediated by the SAYP factor, whose evolutionarily conserved activation domain SAY can directly bind to both BAP170 subunit of Brahma and TAF5 subunit of TFIID. The integrity of BTFly is crucial for its ability to activate transcription. BTFly is distributed genome-wide and appears to be a means of effective transcription activation.coactivators ͉ protein complex A ctivation of transcription by eukaryotic RNA polymerase II (Pol II) requires different groups of coactivators (for reviews, see refs. 1 and 2). The primary function of coactivators is to remodel and modify the chromatin template. Thus, chromatin remodelers of the Brahma (SWI/SNF-related) family play a genome-wide role in activation of Pol II-transcribed genes (3, 4). One more function of coactivators is to further recruit general transcription factors (GTFs) to form the Pol II preinitiation complex. The TFIID coactivator performs this function for most of Pol II-dependent genes (5, 6).Different coactivators recruited to the promoter assist each other and interact in a highly organized gene-specific manner (for a review, see ref. 7). However, this important regulatory step is still poorly understood. The best studied model is that of successive one-by-one recruitment of coactivators, which, in particular, is confirmed by the fact that the recruitment of chromatin-remodeling complexes is usually a prerequisite for the efficient recruitment of GTFs to the promoter (8, 9). The opposite model proposes one-time recruitment of preexisting supercomplex of several coactivators (10-12), although the composition of such supercomplexes described to date appears to be either ambiguous or incomplete.We have described the coactivator SAYP in Drosophila (13). SAYP is present at numerous sites on polytene chromosomes and colocalizes with Pol II in transcriptionally active euchromatin. SAYP homologs in various metazoans have an evolutionarily conserved core containing the SAY domain, which is involved in transcription activation, and 2 PHD fingers (13). Recently, SAYP was found to be associated with the chromatinremodeling Brahma complex of the PBAP subfamily (14). Here, we show that SAYP interacts both with Brahma and with TFIID, assembling them into a stable supercomplex named BTFly (Brahma and TFIID in one assembly). The presence of all BTFly components is crucial for its function in transcription activation. An important fact is that highly purified BTFly contains the full set of TFIID and Brahma subunits and, t...

Bap170, a Subunit of the Drosophila PBAP Chromatin Remodeling Complex, Negatively Regulates the EGFR Signaling

“…Interestingly, both in vivo and in S2 cell, Bap170 is required for stability of Bap180 (Moshkin et al 2007;) and the stability of Bap170, in turn, depends on Sayp (Chalkley et al 2008). The crucial role of Bap170 for PBAP function has also been demonstrated by the recent finding that Bap170 is essential to anchor the PBAP complex to the transcriptional initiator factor TFIID, allowing the formation of the transcriptional supercomplex BTfly (Vorobyeva et al 2009).…”

SWI/SNF Chromatin Remodeling Complex Involved in RNA Polymerase II Elongation Process in Drosophila melanogaster

“…The interplay between chromatin remodeling and general transcriptional factors is so close, that these complexes may unite into physically stable formations termed supercomplexes [5]. An example of such cooperation has been demonstrated for the Drosophila SWI/SNF (dSWI/SNF) and TFIID complexes with the SAYP coactivator as a linchpin unit [6].…”

“…For one ChIP experiment 3x10 6 of S2 Schneider cells were taken. Crosslinking was made by 15 min incubation with 1,5% formaldehyde and was stopped by addition of 1/20 volume of the 2,5M glycine.…”

SAYP interacts with DHR3 nuclear receptor and participates in ecdysone-dependent transcription regulation

“…8 BTFly activates transcription when recruited to the promoters and is functionally indivisible. SAYP is located at multiple sites on the polytene chromosomes of Drosophila larvae, 5,6 indicating that the above mechanism of transcription is apparently widespread. However, no specific activators involved in this mechanism have been identified until recently.…”

“…We have demonstrated that SAYP acts as a component of stable coactivator supercomplex BTFly, which consists of SAYP, Brahma and TFIID coactivators. 5,6 Brahma is the main chromatin-remodeling enzyme playing a genome-wide role in activation of Pol II-transcribed genes, 7 while TFIID is the key transcription initiation factor for most of Pol II-dependent genes. 8 BTFly activates transcription when recruited to the promoters and is functionally indivisible.…”