9fn3

Publication Abstract from PubMed

Ribozymes that catalyze site-specific RNA modification have recently gained increasing interest for their ability to mimic methyltransferase enzymes and for their application to install molecular tags. Recently, we reported SAMURI as a site-specific alkyltransferase ribozyme using S-adenosylmethionine (SAM) or a stabilized analog to transfer a methyl or propargyl group to N(3) of an adenosine. Here, we report the crystal structures of SAMURI in the postcatalytic state. The structures reveal a three-helix junction with the catalytic core folded into four stacked layers, harboring the cofactor and the modified nucleotide. Detailed structure-activity analyses explain the cofactor scope and the structural basis for site selectivity. A structural comparison of SAMURI with SAM riboswitches sheds light on how the synthetic ribozyme overcomes the strategies of natural riboswitches to avoid self-methylation. Our results suggest that SAM and its analogs may serve as substrates for various RNA-catalyzed reactions, for which the corresponding ribozymes remain to be identified.

Structure and catalytic activity of the SAM-utilizing ribozyme SAMURI.,Chen HA, Okuda T, Lenz AK, Scheitl CPM, Schindelin H, Hobartner C Nat Chem Biol. 2025 Jan 8. doi: 10.1038/s41589-024-01808-w. PMID:39779902^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.