The repressive role of H2A.Z variant in transcriptional regulation depends on AtBMI1 activity in Arabidopsis

H2A.Z variant has emerged as a critical player in regulating plant responses to environment; however, the mechanism by which H2A.Z mediates this regulation remains unclear. In Arabidopsis, H2A.Z has been proposed to have opposite effects on transcription depending on its localization within the gene. These opposite roles have been assigned by correlating gene expression and H2A.Z enrichment analyses but without considering the impact of possible H2A.Z posttranslational modifications. Here we show that H2A.Z can be monoubiquitinated by the PRC1 components AtBMI1A/B/C. The incorporation of this modification is required for H2A.Z-mediated transcriptional repression through a mechanism that does not require PRC2 activity. Our data suggest that the dual role of H2A.Z in regulating gene expression depends on the modification that it carries, while the levels of H2A.Z within genes depend on the transcriptional activity. Overall design: mRNA profiles of 7DAG Arabidopsis seedlings Col-0; doble mutant hta9hta11 ; hta9hta11_FLAG-HTA9_N, hta9hta11_FLAG-HTA9_RR and weak double mutant atbmi1ab_weak

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