Swd2/Cps35 determines H3K4 tri-methylation via interactions with Set1 and Rad6_H3K4me3 ChIPseq in WT and several strains
Histone H3K4 tri-methylation (H3K4me3) catalyzed by Set1/COMPASS, is a prominent epigenetic mark found in promoter-proximal regions of actively transcribed genes. H3K4me3 relies on prior monoubiquitination at the histone H2B (H2Bub) by Rad6 and Bre1. Swd2/Cps35, a Set1/COMPASS component, has been proposed as a key player in facilitating H2Bub-dependent H3K4me3. However, a more comprehensive investigation regarding the relationship among Rad6, Swd2 and Set1 is required to further understand the mechanisms and functions of the H3K4 methylation. We investigated the genome-wide occupancy patterns of Rad6, Swd2 and Set1 under various genetic conditions, aiming to clarify the roles of Set1 and Rad6 for occupancy of Swd2. Swd2 peaks appear on both 5'region and 3'region of genes, which are overlapped with its tightly bound two complexes, Set1 and CPF (Cleavage and Polyadenylation Factor), respectively. In the absence of Rad6/H2Bub, Set1 predominantly localized to the  5' region of genes, while Swd2 lost all the chromatin binding. However, in the absence of Set1, Swd2 occupancy near the 5'region was impared and rather increased in the 3' region. This study highlights that catalytic activity of Rad6 is essential for all the ways of Swd2's binding to the transcribed genes and Set1 redistributes the Swd2 to 5'region for accomplishments of H3K4me3 in the genome-wide level. Overall design: Chromatin immunoprecipitation DNA sequencing (ChIP-seq) for histone modifications H3K4me3 in WT and several strains in Saccharomyces cerevisiae. Please note that processed data file generated from both replicates is linked to the corresponding *rep1 sample records.