The GTE4-EML chromatin reader complex concurrently recognizes histone acetylation and H3K4 trimethylation in Arabidopsis.

Histone acetylation and H3K4 trimethylation (H3K4me3) are associated with active transcription. However, how they cooperate to regulate transcription in plants remains largely unclear. Our study revealed that GLOBAL TRANSCRIPTION FACTOR GROUP E 4 (GTE4) binds to acetylated histones and forms a complex with the functionally redundant H3K4me3-binding EMSY-like proteins EML1 or EML2 (EML1/2) in Arabidopsis thaliana. The eml1 eml2 (eml1/2) double mutant exhibits a similar morphological phenotype to gte4, and most of the differentially expressed genes in gte4 were coregulated in eml1/2. Through chromatin immunoprecipitation followed by deep sequencing, we found that GTE4 and EML2 co-occupy protein-coding genes enriched with both histone acetylation and H3K4me3, exerting a synergistic effect on the association of the GTE4-EML complex with chromatin. The association of GTE4 with chromatin requires both its bromodomain and EML-interacting domain. This study identified a complex and uncovered how it concurrently recognizes histone acetylation and H3K4me3 to facilitate gene transcription at the whole-genome level in Arabidopsis.