PMID: 32327602
Michael AK, Grand RS, Isbel L, Cavadini S, Kozicka Z, Kempf G, Bunker RD, Schenk AD, Graff-Meyer A, Pathare GR, Weiss J, Matsumoto S, Burger L, Schubeler D, Thoma NH
Mechanisms of OCT4-SOX2 motif readout on nucleosomes.
Science. 2020 Apr 23. pii: science.abb0074. doi: 10.1126/science.abb0074.
Transcription factors (TFs) regulate gene expression through chromatin where nucleosomes restrict DNA access. To study how TFs bind nucleosome-occupied motifs we focused on the reprogramming factors OCT4 and SOX2. We determined TF engagement throughout a nucleosome at base-pair resolution in vitro, enabling cryo-EM structure determination at two preferred positions. Depending on motif location, OCT4-SOX2 differentially distort nucleosomal DNA. At one position, OCT4-SOX2 removes DNA from Histone H2A/Histone H3 (H2A/H3); however, at an inverted motif, the TFs only induce local DNA distortions. OCT4 uses one of its two DNA binding domains to engage DNA in both structures, reading-out a partial motif. These findings explain site specific nucleosome engagement by the pluripotency factors OCT4-SOX2 and reveal how TFs distort nucleosomes to access chromatinized motifs.