InterPro domain: IPR038459

This entry represents a domain found in class IV SAM-dependent methyltransferases TRM10-type [ 1 ]. Methyltransferases classified as class IV (SPOUT) are homodimers and methylate only RNA. The common core of the SPOUT fold contains a five-stranded beta sheet, flanked by two layers of alpha helices. The core can be divided into two subdomains, both displaying an alpha/beta architecture: (1) the N-terminal strands exhibit a Rossmanoidal alpha/beta fold while (2) an important part of the C-terminal (~ 30 residues) is tucked back into the structure forming a conserved topological trefoil knot where SAM binding occurs. The active site, located at the interface of the two subunits, isformed by amino acids from both monomers [ 2 , 3 ].

TRM10-type methyltransferases include tRNA (guanine(9)-N(1))-methyltransferase, tRNA (adenine(9)-N(1))-methyltransferase and RNA (guanine-9-)-methyltransferase domain-containing protein. TRM10 homologues are widely found in eukaryotes and archaea, but not in bacteria.

1. Crystal structure of tRNA m1G9 methyltransferase Trm10: insight into the catalytic mechanism and recognition of tRNA substrate. Nucleic Acids Res.
2. Many paths to methyltransfer: a chronicle of convergence. Trends Biochem. Sci. 28, 329-35
3. Structural and evolutionary bioinformatics of the SPOUT superfamily of methyltransferases. BMC Bioinformatics 8, 73