Discovery of the β-barrel–type RNA methyltransferase responsible forN6-methylation ofN6-threonylcarbamoyladenosine in tRNAs | Zendy

Satoshi Kimura | Zendy; Kenjyo Miyauchi | Zendy; Yoshiho Ikeuchi | Zendy; Patrick C. Thiaville | Zendy; Valérie de CrécyLagard | Zendy; Tsutomu Suzuki | Zendy

Open Access

Discovery of the β-barrel–type RNA methyltransferase responsible forN⁶-methylation ofN⁶-threonylcarbamoyladenosine in tRNAs

Author(s) -

Satoshi Kimura,

Kenjyo Miyauchi,

Yoshiho Ikeuchi,

Patrick C. Thiaville,

Valérie de CrécyLagard,

Tsutomu Suzuki

Publication year - 2014

Publication title -

nucleic acids research

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 9.008

H-Index - 537

eISSN - 1362-4954

pISSN - 0305-1048

DOI - 10.1093/nar/gku618

Subject(s) - biology , methylation , rna , methyltransferase , transfer rna , microbiology and biotechnology , dna methylation , barrel (horology) , dna , genetics , gene , gene expression , materials science , composite material

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.

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