3av6
Crystal structure of mouse DNA methyltransferase 1 with AdoMet
Structural highlights
FunctionDNMT1_MOUSE Methylates CpG residues. Preferentially methylates hemimethylated DNA. Associates with DNA replication sites in S phase maintaining the methylation pattern in the newly synthesized strand, that is essential for epigenetic inheritance. Associates with chromatin during G2 and M phases to maintain DNA methylation independently of replication. It is responsible for maintaining methylation patterns established in development. DNA methylation is coordinated with methylation of histones. Mediates transcriptional repression by direct binding to HDAC2. In association with DNMT3B and via the recruitment of CTCFL/BORIS, involved in activation of BAG1 gene expression by modulating dimethylation of promoter histone H3 at H3K4 and H3K9.[1] [2] [3] Publication Abstract from PubMedMethylation of cytosine in DNA plays a crucial role in development through inheritable gene silencing. The DNA methyltransferase Dnmt1 is responsible for the propagation of methylation patterns to the next generation via its preferential methylation of hemimethylated CpG sites in the genome; however, how Dnmt1 maintains methylation patterns is not fully understood. Here we report the crystal structure of the large fragment (291-1620) of mouse Dnmt1 and its complexes with cofactor S-adenosyl-L-methionine and its product S-adenosyl-L-homocystein. Notably, in the absence of DNA, the N-terminal domain responsible for targeting Dnmt1 to replication foci is inserted into the DNA-binding pocket, indicating that this domain must be removed for methylation to occur. Upon binding of S-adenosyl-L-methionine, the catalytic cysteine residue undergoes a conformation transition to a catalytically competent position. For the recognition of hemimethylated DNA, Dnmt1 is expected to utilize a target recognition domain that overhangs the putative DNA-binding pocket. Taking into considerations the recent report of a shorter fragment structure of Dnmt1 that the CXXC motif positions itself in the catalytic pocket and prevents aberrant de novo methylation, we propose that maintenance methylation is a multistep process accompanied by structural changes. Structural insight into maintenance methylation by mouse DNA methyltransferase 1 (Dnmt1).,Takeshita K, Suetake I, Yamashita E, Suga M, Narita H, Nakagawa A, Tajima S Proc Natl Acad Sci U S A. 2011 May 31;108(22):9055-9. Epub 2011 Apr 25. PMID:21518897[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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