GSE99390
Structural basis for DNMT3A-mediated de novo DNA methylation (eRRBS)
DNA methylation by de novo DNA methyltransferases 3A (DNMT3A) and 3B (DNMT3B) is essential for genome regulation and development. Dysregulation of this process is implicated in various diseases, notably cancer. However, the mechanisms underlying DNMT3 substrate recognition and enzymatic specificity remain elusive. Here we report a 2.65-Å crystal structure of the DNMT3A-DNMT3L-DNA complex where two DNMT3A monomers simultaneously attack two CpG dinucleotides, with the target sites separated by fourteen base pairs within the same DNA duplex. The DNMT3A-DNA interaction involves a target recognition domain (TRD), a catalytic loop and DNMT3A homodimeric interface. A TRD residue Arg836 makes crucial contact with CpG, ensuring DNMT3A enzymatic preference towards CpG sites in cells. Hematological cancer-associated somatic mutations at the substrate-binding sites decrease DNMT3A activity, induce CpG hypomethylation and promote transformation of hematopoietic cells. Together, our study reveals the mechanistic basis for DNMT3A-mediated DNA methylation and establishes its etiologic link to human disease. Overall design: Dnmt1, Dnmt3a and Dnmt3b triple knockout (TKO) mouse embryonic stem cells were stably expressed with wild-type or R836A mutant DNMT3A. Genomic DNA was extracted and analyzed by eRRBS.