Specificity of Dnmt1 for methylation of hemimethylated CpG sites resides in its catalytic domain.
The maintenance methylation of hemimethylated CpG sites by the DNA methyltransferase Dnmt1 is the molecular basis of the inheritance of DNA methylation patterns. Based on structural data and kinetics obtained with a truncated form of Dnmt1, an autoinhibition model for the specificity of Dnmt1 was proposed in which unmethylated DNA binds to Dnmt1's CXXC domain, which prevents its methylation. We have prepared CXXC domain variants that lost DNA binding. Corresponding full-length Dnmt1 variants did not display a reduction in specificity, indicating that the autoinhibition model does not apply in full-length Dnmt1. Furthermore, we show that the Dnmt1 M1235S variant, which carries an exchange in the catalytic domain of the enzyme, has a marked reduction in specificity, indicating that the recognition of the hemimethylated state of target sites resides within the catalytic domain.
Institute of Biochemistry, Faculty of Chemistry, University Stuttgart, 70569 Stuttgart, Germany.
Pavel
P
Bashtrykov
Gytis
G
Jankevicius
Anita
A
Smarandache
Renata Z
RZ
Jurkowska
Sergey
S
Ragozin
Albert
A
Jeltsch
D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D018899:CpG Islands; D004247:DNA / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D008969:Molecular Sequence Data; D009154:Mutation; D016415:Sequence Alignment; D013379:Substrate Specificity
D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases