Comparative interactome analysis of the PRE DNA-binding factors: purification of the Combgap, Zeste, Psq, and Adf1 associated proteins

To gain an insight into the PRE DNA-binding protein regulatory network, here, using immunoaffinity purification coupled to the high throughput mass spectrometry, we isolated factors associated with the Combgap, Psq, Zeste and Adf1 PRE DNA-binding proteins. We show that Combgap and Zeste are more tightly associated with the Polycomb repressive complex 1 (PRC1), while Psq interacts strongly with the TrxG proteins, including the BAP SWI/SNF complex. The Adf1 interactome contained Mediator subunits as the top interactors. In addition, Combgap efficiently interacted with AGO2, NELF, and TFIID. Combgap, Psq, and Adf1 have architectural proteins in their networks. We further investigated the existence of direct interactions between different PRE DNA-binding proteins and demonstrated that Combgap-Adf1, Psq-Dsp1, and Pho-Spps can interact in the yeast two-hybrid assay. Overall, our data suggest that Combgap, Psq, Zeste and Adf1 are associated with the protein complexes implicated in different regulatory activities and indicate their potential multifunctional role in the regulation of transcription. ChIP-seq of Combgap, Zeste, Psq, and Adf1 in S2 cells