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The human Dnmt2 has residual DNA-(cytosine-C5) methyltransferase activity
Andrea Hermann1, Sigrid Schmitt, Albert Jeltsch
1Institut für Biochemie, FB 8, Heinrich-Buff-Ring 58, Justus-Liebig-Universität, 35392 Giessen, Germany.
Abstract:
The human Dnmt2 protein is one member of a protein family conserved from Schizosaccharomyces pombe and Drosophila melanogaster to Mus musculus and Homo sapiens. It contains all of the amino acid motifs characteristic for DNA-(Cytosine-C5) methyltransferases, and its structure is very similar to prokaryotic DNA methyltransferases. Nevertheless, so far all attempts to detect catalytic activity of this protein have failed. We show here by two independent assay systems that the purified Dnmt2 protein has weak DNA methyltransferase activity. Methylation was observed at CG sites in a loose ttnCGga(g/a) consensus sequence, suggesting that Dnmt2 has a more specialized role than other mammalian DNA methyltransferases.
Insights
Researchers discovered that the human Dnmt2 protein, despite previous failures to detect its activity, possesses weak DNA methyltransferase capabilities. This finding suggests a specialized role for Dnmt2 in DNA methylation processes.
Area of Science:
- Molecular Biology
- Epigenetics
- Enzymology
Background:
- The human Dnmt2 protein is a conserved enzyme with structural similarities to DNA methyltransferases.
- Previous studies failed to detect catalytic activity, questioning its function.
- Dnmt2 belongs to a protein family found across diverse species, from yeast to humans.
Purpose of the Study:
- To investigate the catalytic activity of the purified human Dnmt2 protein.
- To determine if Dnmt2 exhibits DNA methyltransferase activity.
- To characterize the DNA methylation activity of Dnmt2.
Main Methods:
- Utilized two independent assay systems to detect enzymatic activity.
- Purified the human Dnmt2 protein for experimental analysis.
- Analyzed methylation patterns at specific DNA sites.
Main Results:
- The purified Dnmt2 protein demonstrated weak DNA methyltransferase activity.
- Methylation was specifically observed at CG sites.
- A consensus sequence 'ttnCGga(g/a)' was identified for Dnmt2 activity.
Conclusions:
- Human Dnmt2 protein possesses DNA methyltransferase activity, contrary to previous findings.
- Dnmt2 exhibits a specialized role in DNA methylation, distinct from other mammalian DNA methyltransferases.
- The identified consensus sequence provides insights into Dnmt2's substrate specificity.