CryoEM structures of Arabidopsis DDR complexes involved in RNA-directed DNA methylation

• Main Authors: Somsakul Pop Wongpalee, Shiheng Liu, Javier Gallego-Bartolomé, Alexander Leitner, Ruedi Aebersold, Wanlu Liu, Linda Yen, Maria A. Nohales, Peggy Hsuanyu Kuo, Ajay A. Vashisht, James A. Wohlschlegel, Suhua Feng, Steve A. Kay, Z. Hong Zhou, Steven E. Jacobsen
• Format: Journal
• Published: 2019
• Subjects: Biochemistry, Genetics and Molecular Biology; Chemistry; Physics and Astronomy
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85071718637&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/66578
• Institution: Chiang Mai University

© 2019, The Author(s). Transcription by RNA polymerase V (Pol V) in plants is required for RNA-directed DNA methylation, leading to transcriptional gene silencing. Global chromatin association of Pol V requires components of the DDR complex DRD1, DMS3 and RDM1, but the assembly process of this complex and the underlying mechanism for Pol V recruitment remain unknown. Here we show that all DDR complex components co-localize with Pol V, and we report the cryoEM structures of two complexes associated with Pol V recruitment—DR (DMS3-RDM1) and DDR′ (DMS3-RDM1-DRD1 peptide), at 3.6 Å and 3.5 Å resolution, respectively. RDM1 dimerization at the center frames the assembly of the entire complex and mediates interactions between DMS3 and DRD1 with a stoichiometry of 1 DRD1:4 DMS3:2 RDM1. DRD1 binding to the DR complex induces a drastic movement of a DMS3 coiled-coil helix bundle. We hypothesize that both complexes are functional intermediates that mediate Pol V recruitment.