Uncovering the DNA‐binding Properties of the GATA4 and TBX5 Cardiac Transcription Factor Complex

Transcription factors (TFs) are essential gene regulators of cellular differentiation and organ development. Eukaryotic TFs are notorious for often binding DNA as multimeric protein complexes to regulate gene expression. GATA4 and TBX5 are transcription factors that are central components of the gene regulatory network of human heart development. Recent studies have determined the binding specificity of these transcription factors as monomers. However, the DNA‐binding properties of the cooperative complex between GATA4 and TBX5 remain undetermined. Based on this, we wanted to know the heteromeric complex's DNA recognition grammar rules such as the spacing and orientation between each protein's binding sequence. We determined the in vitro DNA‐binding specificity of the GATA4:TBX5 complex using Systematic Evolution of Ligands by Exponential Enrichment (SELEX‐seq). Our preliminary results demonstrate that the TF monomeric binding motifs differ in length from the DNA‐binding sequences recognized by the heteromeric complex. Additionally, the DNA logos show that the GATA4:TBX5 cooperative complex has spacing and orientation preferences. Based on the enrichment fold, this cooperative complex prefers a 3bp spacer and a head‐to‐tail orientation. We will validate these binding sites through biochemical experiments. The findings of this study will help us understand the DNA‐recognition rules of the GATA4:TBX5 complex and its potential roles in normal human heart development.