rsmD

RsmD, or ribosomal small subunit methyltransferase D, is a bacterial enzyme that participates in the post-transcriptional modification of the 16S ribosomal RNA, a component of the 30S subunit of the ribosome. It is an S-adenosyl-L-methionine (SAM)-dependent methyltransferase that transfers a methyl group to guanine bases within the 16S rRNA.

Functionally, RsmD methylates conserved guanine residues in the 16S rRNA and contributes to proper ribosome assembly and translation fidelity. In many bacteria, it works in coordination with other rRNA modification enzymes to install specific methyl marks in the decoding region of the small subunit, influencing the performance of the ribosome during translation.

Structurally, RsmD belongs to the Rossmann-like fold family of methyltransferases. It binds SAM as the methyl donor and interacts with the 16S rRNA substrate, with catalytic motifs characteristic of bacterial rRNA methyltransferases. The enzyme is typically studied in the context of bacterial models in which ribosome biogenesis and modification pathways have been characterized.

Genetically, the rsmD gene is usually found within operons related to ribosome biogenesis or rRNA modification. Its expression can be influenced by growth conditions and cellular stress, reflecting the link between ribosome maturation and environmental adaptation.

Distribution and evolution show that RsmD is widely conserved among bacteria, with orthologs appearing across diverse lineages, indicating an ancient and broadly important role in ribosome biogenesis.

See also: rRNA methyltransferases, RsmB, ribosome biogenesis.