Molecular interactions of ada proteins, as a component of histone acetyl transferase complexes

In eukaryotes, the repressive nature of chromatin can be relieved by chromatin remodeling and histone-modifying activities, which require intensive protein-protein interactions among its components. These activities alter chromatin structure making it accessible to, and recognized by the components of the RNA polymerase II-mediated transcriptional machinery. Therefore, molecular interactions involved in modulating the structure of chromatin play an important role in transcriptional regulation. Alteration/Deficiency in Activation (ADA) proteins function in transcriptional initiation site selection, interacting with basal transcription factors, and facilitating acetylation of the nucleosomal histones as the components of ADA/GCN5 histone acetyltransferase (HAT) complexes. Our laboratory previously, identified four new novel interacting partners of human ADA3 (hADA3), namely AATF, PHF21A, and regulatory subunits of the protein phosphatases PP1 and PP2A (PPP1R7 and PPP2R5D, respectively) via yeast 2 hybrid (Y2H) library screening. Based on these findings, our hypothesis is a prospective interaction potential of these partners with human ADA2 (hADA2) that was involved in the same complex with known interaction with hADA3 due to its functions. We, therefore, tested these interactions with hADA2 with Y2H technology to address their functional significance in hADA3 containing complexes in this study. Our results supported our hypothesis that hADA2 participate in hADA3 interaction network. The pulled interactions are discussed in relation to the potential significance of the new possible pathways regulated by ADA/GCN5 HAT complexes. Key Words; Human-ADA3; -ADA2; yeast 2 hybrid; chromatin remodeling, transcriptional regulation