CpG methyltransferase
DNA methyltransferase enzyme
M.SssI (EC 2.1.1.37) is a DNA (cytosine-5)-methyltransferase that methylates cytosine residues at the C5 position within the dinucleotide sequence 5'-CG-3' (commonly abbreviated as CpG). It originates from the bacterium Spiroplasma sp. strain MQ1. M.SssI methylates all CpG sites in DNA, regardless of their methylation status (unmethylated or hemimethylated). This enzyme utilizes S-adenosyl-L-methionine (SAM) as the methyl group donor. Due to its ability to methylate CpG sites with high efficiency, mimicking the patterns of DNA methylation found in higher eukaryotes, M.SssI is a frequently used tool in epigenetics research.
Enzymology
M.SssI is a prokaryotic DNA methyltransferase that specifically recognizes the CpG dinucleotide. Unlike many bacterial methyltransferases that are part of a restriction modification system, M.SssI is often referred to as an "orphan" methyltransferase because its corresponding restriction enzyme in Spiroplasma has not been well-characterized or may not exist in a typical defense context. The enzyme is capable of methylating both strands of a CpG site. It can act on unmethylated DNA, introducing methylation de novo, and on hemimethylated DNA (where only one strand is methylated), thereby completing the methylation pattern.
Begin with the source’s own compact description: “CpG methyltransferase” is dNA methyltransferase enzyme. The dossier treats that line as a proposition to test through methyltransferase and enzyme, not as a finished interpretation.
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This entry incorporates text from “CpG methyltransferase” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.