RESUMO
DNA methylation mediates silencing of transposable elements and genes in part via recruitment of the Arabidopsis MBD5/6 complex, which contains the methyl-CpG binding domain (MBD) proteins MBD5 and MBD6, and the J-domain containing protein SILENZIO (SLN). Here, we characterize two additional complex members: α-crystalline domain (ACD) containing proteins ACD15 and ACD21. We show that they are necessary for gene silencing, bridge SLN to the complex, and promote higher-order multimerization of MBD5/6 complexes within heterochromatin. These complexes are also highly dynamic, with the mobility of MBD5/6 complexes regulated by the activity of SLN. Using a dCas9 system, we demonstrate that tethering the ACDs to an ectopic site outside of heterochromatin can drive a massive accumulation of MBD5/6 complexes into large nuclear bodies. These results demonstrate that ACD15 and ACD21 are critical components of the gene-silencing MBD5/6 complex and act to drive the formation of higher-order, dynamic assemblies at CG methylation (meCG) sites.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Proteínas de Ligação a DNA/metabolismo , Heterocromatina/genética , Heterocromatina/metabolismo , Elementos de DNA Transponíveis/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Metilação de DNA , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismoRESUMO
DNA methylation mediates silencing of transposable elements and genes in part via recruitment of the Arabidopsis MBD5/6 complex, which contains the methyl-CpG-binding domain (MBD) proteins MBD5 and MBD6, and the J-domain containing protein SILENZIO (SLN). Here we characterize two additional complex members: α-crystalline domain containing proteins ACD15 and ACD21. We show that they are necessary for gene silencing, bridge SLN to the complex, and promote higher order multimerization of MBD5/6 complexes within heterochromatin. These complexes are also highly dynamic, with the mobility of complex components regulated by the activity of SLN. Using a dCas9 system, we demonstrate that tethering the ACDs to an ectopic site outside of heterochromatin can drive massive accumulation of MBD5/6 complexes into large nuclear bodies. These results demonstrate that ACD15 and ACD21 are critical components of gene silencing complexes that act to drive the formation of higher order, dynamic assemblies.
