2Omethylation

2Omethylation is a term used to describe the introduction of a methyl group onto an oxygen atom at a defined position in a molecule. Because many biological and chemical substrates contain multiple oxygen atoms, the exact site of methylation matters, with common references including 2'-O-methylation in RNA and 2-O-methylation in carbohydrates and related compounds. The phrase is encountered in biochemistry and organic chemistry to denote this class of modifications.

In nucleic acids, the most studied form is 2'-O-methylation of the ribose sugar in RNA nucleotides. This modification adds a methoxy group at the 2' position of the sugar and is found in various RNA species, including rRNA, tRNA, and some snRNA. In eukaryotes, 2'-O-methylation is often guided by small nucleolar RNAs (snoRNAs) as part of C/D box snoRNPs, with fibrillarin serving as the catalytic methyltransferase. In bacteria, 2'-O-methylation is performed by a family of 2'-O-methyltransferases such as FtsJ/RrmJ. S-adenosyl-L-methionine (SAM) is the common methyl donor. The modification can increase RNA stability, influence base pairing and structure, and affect interactions with proteins and the ribosome. Mapping and analysis employ mass spectrometry, nuclear magnetic resonance, and sequencing-based approaches.

Outside nucleic acids, 2-O-methylation also occurs on sugar moieties within glycans and natural products, affecting properties such as solubility, enzymatic recognition, and bioactivity. In virology and immunology, cap 2'-O-methylation of viral transcripts is known to aid in evading host immune responses. Overall, 2Omethylation encompasses a family of oxygen-targeted methylations with diverse biological and chemical implications.