Mediator12 and 13 act as conditional anti-silencing factors in Arabidopsis [ChIP-seq]

Mediator is a multi-protein complex which facilitates the initial steps of gene transcription. Mediator 12 (MED12) and MED13 are components of a module that reversibly associates with the core Mediator complex, and both positively and negatively regulates gene expression. Here, in an Arabidopsis mutant screen for factors that can bypass repressive epigenetic marks, we identified MED12 and MED13 as anti-silencing factors. Both are preferentially required for the expression of genes in the absence of H3K4me3, an activating chromatin mark. Thus, MED12 and MED13 respond to specific epigenetic states and can act as conditional positive gene regulators in Arabidopsis. Overall design: GFP-wt_H3K4me3 was normalized to GFP-wt_H3. GFP-morc1_H3K4me3 was normalized to GFP-morc1-H3. GFP-ddc_H3K4me3 was normalized to GFP-ddc_H3. MED12-YFP-FLAG was normalized to columbia-0_FLAG.