Discovery of the β-barrel-type RNA Methyltransferase Responsible for N6-methylation of N6-threonylcarbamoyladenosine in TRNAs
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Methylation is a versatile reaction involved in the synthesis and modification of biologically active molecules, including RNAs. N(6)-methyl-threonylcarbamoyl adenosine (m(6)t(6)A) is a post-transcriptional modification found at position 37 of tRNAs from bacteria, insect, plants, and mammals. Here, we report that in Escherichia coli, yaeB (renamed as trmO) encodes a tRNA methyltransferase responsible for the N(6)-methyl group of m(6)t(6)A in tRNA(Thr) specific for ACY codons. TrmO has a unique single-sheeted β-barrel structure and does not belong to any known classes of methyltransferases. Recombinant TrmO employs S-adenosyl-L-methionine (AdoMet) as a methyl donor to methylate t(6)A to form m(6)t(6)A in tRNA(Thr). Therefore, TrmO/YaeB represents a novel category of AdoMet-dependent methyltransferase (Class VIII). In a ΔtrmO strain, m(6)t(6)A was converted to cyclic t(6)A (ct(6)A), suggesting that t(6)A is a common precursor for both m(6)t(6)A and ct(6)A. Furthermore, N(6)-methylation of t(6)A enhanced the attenuation activity of the thr operon, suggesting that TrmO ensures efficient decoding of ACY. We also identified a human homolog, TRMO, indicating that m(6)t(6)A plays a general role in fine-tuning of decoding in organisms from bacteria to mammals.
Lin W, Zhang Z, Wang C, Ye Y, Zheng L, Hu Q Nat Sci Sleep. 2025; 17:413-424.
PMID: 40078878 PMC: 11903111. DOI: 10.2147/NSS.S495422.
Yamamura R, Nagayoshi Y, Nishiguchi K, Kaneko H, Yamamoto K, Matsushita K mBio. 2024; 16(1):e0312424.
PMID: 39660929 PMC: 11708014. DOI: 10.1128/mbio.03124-24.
The modification landscape of tRNAs.
Mandler M, Maligireddy S, Guiblet W, Fitzsimmons C, McDonald K, Warrell D RNA. 2024; 30(8):1025-1040.
PMID: 38684317 PMC: 11251520. DOI: 10.1261/rna.080004.124.
The modification landscape of tRNAs.
Mandler M, Maligireddy S, Guiblet W, Fitzsimmons C, McDonald K, Warrell D bioRxiv. 2024; .
PMID: 38529508 PMC: 10962704. DOI: 10.1101/2024.02.21.581370.
Investigations of Single-Subunit tRNA Methyltransferases from Yeast.
Wang Z, Xu X, Li X, Fang J, Huang Z, Zhang M J Fungi (Basel). 2023; 9(10).
PMID: 37888286 PMC: 10608323. DOI: 10.3390/jof9101030.