Identifying a TFIID interactome via integrated biochemical and high-throughput proteomic studies

The core promoter recognition TFIID complex acts as a central regulator for eukaryotic gene expression. To direct transcription initiation, TFIID binds the core promoter DNA and aids recruitment of the transcription machinery (e.g., RNA polymerase II) to the transcription start site. Many transcription factors target TFIID to control vital cellular processes. Current studies on finding TFIID interactors have predominantly focused on transcription factors. Yet, a comprehensive interactome of mammalian TFIID has not been established. Therefore, this study sought to reveal potential TFIID-nucleated networks by identifying likely co-regulatory factors that bind TFIID. By using intact native human TFIID complexes, we have exploited three independent approaches including a high-throughput Next Generation DNA sequencing coupled with proteomic analysis. Among these methods, we found some overlapping and new candidates in which we further assessed three putative interactors (i.e., Sox2, H2A and EMSY) by co-immunoprecipitation assays. Notably, in addition to known TFIID interactors, we identified a number of novel factors that participate either in co-regulatory pathways or non-transcription related functions of TFIID. Overal, these results indicate that, in addition to transcription initiation, mammalian TFIID may be involved in broader regulatory pathways than previous studies suggested.