Intrinsically disordered regions restrain genomic targeting of RNA and histone demethylases in mammals and plants [Histone_ALKBH]

Intrinsically disordered regions (IDRs) are well-known facilitators of chromatin regulation, but their role as regulatory restraints remains underexplored. Here, we reveal that the C-terminal IDR of mammalian ALKBH5 anchors its main activity to mRNA, limiting chromatin engagement in mouse embryonic stem cells (mESCs). IDR deletion redirects ALKBH5 to chromatin-associated non-coding RNAs, driving widespread chromatin opening and transcriptional activation. This mechanism extends to histone demethylases, where IDR deletion also results in broad removal of repressive histone marks, leading to increased chromatin accessibility and activation of transposable elements. Leveraging these insights, we engineered ALKBH5 and its plant homologs with IDR deletion. Overexpression of these IDR-deleted ALKBH5 demethylases could promote Arabidopsis root growth and increase rice yield. Our findings uncover a conserved role for IDRs in restraining chromatin access by RNA and histone demethylases and establish a new strategy of chromatin programming for crop engineering using plant proteins.