Fig. 4
From: CryoEM structures of Arabidopsis DDR complexes involved in RNA-directed DNA methylation

Possible assembly pathway of the DDR complex that leads to Pol V recruitment. a The assembly characteristics of the DR and DDR′ complex. The DR complex is a prerequisite for binding of DRD1 peptide 7 but can accommodate only a single DRD1 peptide. Steric clash between the two peptides is expected if another DRD1 peptide binds to the complex. HP, hydrophobic pocket of RDM1. b DRD1 binding converts the DMS3 dimer from “open” to “closed” state. Chain names are shown inside the parentheses. c Possible mechanisms of chromatin targeting of the DDR complex and Pol V recruitment. The DDR complex is assembled from binding of DRD1 protein to the DR complex. Pol V is then recruited to the DDR complex through interaction with DRD1. However, it is also possible that Pol V is recruited at the same time as DRD1, as a preformed DRD1-Pol V complex. Chromatin targeting could happen during either step and is likely to be mediated, at least, by interaction between DMS3 and methylated DNA binders SUVH2 or SUVH9