IUBMB Enzyme Nomenclature


Accepted name: 23S rRNA (guanine748-N1)-methyltransferase

Reaction: S-adenosyl-L-methionine + guanine748 in 23S rRNA = S-adenosyl-L-homocysteine + N1-methylguanine748 in 23S rRNA

Other name(s): Rlma(II); Rlma2; 23S rRNA m1G748 methyltransferase; RlmaII; Rlma II; tylosin-resistance methyltransferase RlmA(II); TlrB; rRNA large subunit methyltransferase II

Systematic name: S-adenosyl-L-methionine:23S rRNA (guanine748-N1)-methyltransferase

Comments: The enzyme specifically methylates guanine748 at N1 in 23S rRNA. The methyltransferase RlmAII confers resistance to the macrolide antibiotic tylosin in the drug-producing strain Streptomyces fradiae [1].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Douthwaite, S., Crain, P.F., Liu, M. and Poehlsgaard, J. The tylosin-resistance methyltransferase RlmAII (TlrB) modifies the N-1 position of 23S rRNA nucleotide G748. J. Mol. Biol. 337 (2004) 1073-1077. [PMID: 15046978]

2. Liu, M., Kirpekar, F., Van Wezel, G.P. and Douthwaite, S. The tylosin resistance gene tlrB of Streptomyces fradiae encodes a methyltransferase that targets G748 in 23S rRNA. Mol. Microbiol. 37 (2000) 811-820. [PMID: 10972803]

3. Lebars, I., Yoshizawa, S., Stenholm, A.R., Guittet, E., Douthwaite, S. and Fourmy, D. Structure of 23S rRNA hairpin 35 and its interaction with the tylosin-resistance methyltransferase RlmAII. EMBO J. 22 (2003) 183-192. [PMID: 12514124]

4. Lebars, I., Husson, C., Yoshizawa, S., Douthwaite, S. and Fourmy, D. Recognition elements in rRNA for the tylosin resistance methyltransferase RlmAII. J. Mol. Biol. 372 (2007) 525-534. [PMID: 17673230]

5. Douthwaite, S., Jakobsen, L., Yoshizawa, S. and Fourmy, D. Interaction of the tylosin-resistance methyltransferase RlmAII at its rRNA target differs from the orthologue RlmAI. J. Mol. Biol. 378 (2008) 969-975. [PMID: 18406425]

6. Liu, M. and Douthwaite, S. Methylation at nucleotide G745 or G748 in 23S rRNA distinguishes Gram-negative from Gram-positive bacteria. Mol. Microbiol. 44 (2002) 195-204. [PMID: 11967079]

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