Molecular basis of tRNA substrate recognition and modification by the atypical SPOUT methyltransferase Trm10.

ABSTRACT: The evolutionarily conserved methyltransferase Trm10 modifies the N1 position of guanosine 9 (G9) in some tRNAs, but how the enzyme recognizes and modifies its substrate tRNAs remains unclear. Here, we used an S-adenosyl-L-methionine (SAM) analog to trap the Trm10-tRNA^Gly complex and enable determination of its structure in a post-catalytic state by cryogenic electron microscopy (cryo-EM). We observed three distinct complexes: two with a single Trm10 bound to tRNA that differ in their tRNA acceptor stem orientation ("closed" and "open") and a minor population with two Trm10s engaging the same tRNA. The monomeric complexes reveal a positively charged surface that guides the G9 into the catalytic site with key conserved residues forming "pincer"-like interactions that stabilize th

SUBMITTER: Nandi S 

PROVIDER: S-EPMC12713601 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature