IUBMB Enzyme Nomenclature


Accepted name: 16S rRNA (guanine1405-N7)-methyltransferase

Reaction: S-adenosyl-L-methionine + guanine1405 in 16S rRNA = S-adenosyl-L-homocysteine + N7-methylguanine1405 in 16S rRNA

Other name(s): methyltransferase Sgm; m7G1405 Mtase; Sgm Mtase; Sgm; sisomicin-gentamicin methyltransferase; sisomicin-gentamicin methylase; GrmA; RmtB; RmtC; ArmA

Systematic name: S-adenosyl-L-methionine:16S rRNA (guanine1405-N7)-methyltransferase

Comments: The enzyme specifically methylates guanine1405 at N7 in 16S rRNA. The enzyme from the antibiotic-producing bacterium Micromonospora zionensis methylates guanine1405 in 16S rRNA to 7-methylguanine, thereby rendering the ribosome resistant to 4,6-disubstituted deoxystreptamine aminoglycosides, which include gentamicins and kanamycins [2].

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


1. Husain, N., Tkaczuk, K.L., Tulsidas, S.R., Kaminska, K.H., Cubrilo, S., Maravic-Vlahovicek, G., Bujnicki, J.M. and Sivaraman, J. Structural basis for the methylation of G1405 in 16S rRNA by aminoglycoside resistance methyltransferase Sgm from an antibiotic producer: a diversity of active sites in m7G methyltransferases. Nucleic Acids Res. 38 (2010) 4120-4132. [PMID: 20194115]

2. Savic, M., Lovric, J., Tomic, T.I., Vasiljevic, B. and Conn, G.L. Determination of the target nucleosides for members of two families of 16S rRNA methyltransferases that confer resistance to partially overlapping groups of aminoglycoside antibiotics. Nucleic Acids Res. 37 (2009) 5420-5431. [PMID: 19589804]

3. Tomic, T.I., Moric, I., Conn, G.L. and Vasiljevic, B. Aminoglycoside resistance genes sgm and kgmB protect bacterial but not yeast small ribosomal subunits in vitro despite high conservation of the rRNA A-site. Res. Microbiol. 159 (2008) 658-662. [PMID: 18930134]

4. Savic, M., Ilic-Tomic, T., Macmaster, R., Vasiljevic, B. and Conn, G.L. Critical residues for cofactor binding and catalytic activity in the aminoglycoside resistance methyltransferase Sgm. J. Bacteriol. 190 (2008) 5855-5861. [PMID: 18586937]

5. Maravic Vlahovicek, G., Cubrilo, S., Tkaczuk, K.L. and Bujnicki, J.M. Modeling and experimental analyses reveal a two-domain structure and amino acids important for the activity of aminoglycoside resistance methyltransferase Sgm. Biochim. Biophys. Acta 1784 (2008) 582-590. [PMID: 18343347]

6. Kojic, M., Topisirovic, L. and Vasiljevic, B. Cloning and characterization of an aminoglycoside resistance determinant from Micromonospora zionensis. J. Bacteriol. 174 (1992) 7868-7872. [PMID: 1447159]

7. Schmitt, E., Galimand, M., Panvert, M., Courvalin, P. and Mechulam, Y. Structural bases for 16 S rRNA methylation catalyzed by ArmA and RmtB methyltransferases. J. Mol. Biol. 388 (2009) 570-582. [PMID: 19303884]

8. Wachino, J., Shibayama, K., Kimura, K., Yamane, K., Suzuki, S. and Arakawa, Y. RmtC introduces G1405 methylation in 16S rRNA and confers high-level aminoglycoside resistance on Gram-positive microorganisms. FEMS Microbiol. Lett. 311 (2010) 56-60. [PMID: 20722735]

9. Liou, G.F., Yoshizawa, S., Courvalin, P. and Galimand, M. Aminoglycoside resistance by ArmA-mediated ribosomal 16S methylation in human bacterial pathogens. J. Mol. Biol. 359 (2006) 358-364. [PMID: 16626740]

[EC created 2010]

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