SNAP-annotated 5mC-DNA-protein interactions: PDB entry 7xib

PDB-id

7xib; DSSR-derived features in text and JSON formats; DNAproDB

Class

transferase-DNA

Method

cryo-EM (2.23 Å)

Summary

cryo-EM structure of human dnmt1 (aa:351-1616) in complex with ubiquitinated h3 and hemimethylated DNA analog (cxxc-disordered form)

Reference

Kikuchi A, Onoda H, Yamaguchi K, Kori S, Matsuzawa S, Chiba Y, Tanimoto S, Yoshimi S, Sato H, Yamagata A, Shirouzu M, Adachi N, Sharif J, Koseki H, Nishiyama A, Nakanishi M, Defossez PA, Arita K (2022): "Structural basis for activation of DNMT1." Nat Commun, 13, 7130. doi: 10.1038/s41467-022-34779-4.

Abstract

DNMT1 is an essential enzyme that maintains genomic DNA methylation, and its function is regulated by mechanisms that are not yet fully understood. Here, we report the cryo-EM structure of human DNMT1 bound to its two natural activators: hemimethylated DNA and ubiquitinated histone H3. We find that a hitherto unstudied linker, between the RFTS and CXXC domains, plays a key role for activation. It contains a conserved α-helix which engages a crucial "Toggle" pocket, displacing a previously described inhibitory linker, and allowing the DNA Recognition Helix to spring into the active conformation. This is accompanied by large-scale reorganization of the inhibitory RFTS and CXXC domains, allowing the enzyme to gain full activity. Our results therefore provide a mechanistic basis for the activation of DNMT1, with consequences for basic research and drug design.

• The contacts include paired nucleotides (mostly a G in Watson-Crick G-C pairing) and amino-acids within a 4.5-Å distance cutoff to base atoms of 5mC.
• The structure is oriented in the base reference frame of 5mC, allowing for easy comparison and direct superimposition between entries.
• The black sphere (•) denotes the 5-methyl carbon atom in 5mC.