2Omethyltransferases

2'-O-methyltransferases are enzymes that catalyze the transfer of a methyl group to the 2'-hydroxyl group of the ribose in RNA molecules. The methyl donor is S-adenosyl-L-methionine (SAM), and the reaction produces 2'-O-methylated RNA (Nm) and S-adenosyl-L-homocysteine (SAH). This modification is found in various RNA types, most prominently ribosomal RNA (rRNA) and transfer RNA (tRNA), and also in some small nuclear and other RNA species. 2'-O-methylation can influence RNA stability, structure, and interactions with proteins, with consequences for RNA processing and function.

Enzymes and targeting differ across domains of life. In bacteria, 2'-O-methylation is often performed by standalone enzymes of the FtsJ/RrmJ family, which can modify specific sites on rRNA and are linked to ribosome biogenesis and cell growth. In archaea and eukaryotes, 2'-O-methylation is frequently carried out by box C/D small nucleolar ribonucleoproteins (snoRNPs). In these complexes, fibrillarin serves as the catalytic subunit, and a guide RNA (the box C/D snoRNA) directs the enzyme to the target nucleotide on the ribosomal or other RNA.

Biological significance is broad: Nm marks contribute to proper ribosome assembly and translation fidelity, govern RNA stability, and participate in the broader regulation of gene expression on the RNA level. Defects in 2'-O-methylation pathways can impact cellular growth, stress responses, and organismal development, and are studied in contexts ranging from basic RNA biology to disease.