Genome-wide binding of GATA1 and TAL1 determined at high resolution

Erythroid development and differentiation from multiprogenitor cells to red blood cells requires precise transcriptional regulation. Key erythroid transcription factors, GATA1 and TAL1, co-operate, along with other proteins, to regulate many aspects of this process. How GATA1 and TAL1 are positionally organized with respect to each other and their cognate DNA binding site across the mouse genome remains unclear. We applied high resolution ChIP-exo to GATA1 and TAL1 to study their positional organization across the mouse genome during GATA1-dependent maturation. Two complementary methods, MultiGPS and peak-pairing, were used to determine high confidence binding locations by ChIP-exo. We identified ~10,000 GATA1 and ~15,000 TAL1 locations, which were essentially confirmed by ChIP-seq. Of these, ~4,000 locations were bound by both GATA1 and TAL1. About three-quarters of these were tightly linked (<40 bp away) to a partial E-box located 7-8 bp upstream of a WGATAA motif. Both TAL1 and GATA1 generated distinct characteristic ChIP-exo peaks around WGATAA motifs, that reflect on their positional arrangement within a complex. We show that TAL1 and GATA1 form a precisely organized complex at a compound motif consisting of a TG 7-8 bp upstream of a WGATAA motif across thousands of genomic locations. Genome wide analysis of GATA1 and TAL1 in G1E and G1E-ER4 cells using ChIP-exo experiments