Biology subjects

Piasecka, A.

Publications and source records attributed to Piasecka, A..

2 recordsLinked to original sources

bioRxiv2017

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.

biochemistry↗

bioRxiv2016

p53 dynamically directs TFIID assembly on target gene promoters

The p53 tumor suppressor protein is a central regulator that turns on vast gene networks to maintain cellular integrity upon various stimuli. p53 activates transcription initiation in part by aiding recruitment of TFIID to the promoter. However, the precise means by which p53 dynamically interacts with TFIID to facilitate assembly on target gene promoters remains elusive. To address this key question, we have undertaken an integrated approach involving single molecule fluorescence microscopy, single particle cryo-electron microscopy, and biochemistry. Our real-time single molecule imaging demonstrates that TFIID alone binds poorly to native p53 target promoters. p53 unlocks TFIIDs ability to bind DNA by increasing TFIID contacts with both the core promoter and a region surrounding p53s response element (RE). Analysis of single molecule dissociation kinetics reveals that TFIID interacts with promoters via transient and prolonged DNA binding modes that are each regulated by p53. Importantly, our structural work reveals that TFIIDs conversion from a canonical form to a rearranged DNA-binding conformation is enhanced in the presence of DNA and p53. Notably, TFIIDs interaction with DNA induces p53 to rapidly dissociate, effectively liberating the RE on the promoter. Collectively, these findings indicate that p53 dynamically escorts and loads the basal transcription machinery onto its target promoters.

biochemistry↗