The Enzyme Database

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EC 2.1.1.192     
Accepted name: 23S rRNA (adenine2503-C2)-methyltransferase
Reaction: (1) 2 S-adenosyl-L-methionine + adenine2503 in 23S rRNA + 2 reduced [2Fe-2S] ferredoxin = S-adenosyl-L-homocysteine + L-methionine + 5′-deoxyadenosine + 2-methyladenine2503 in 23S rRNA + 2 oxidized [2Fe-2S] ferredoxin
(2) 2 S-adenosyl-L-methionine + adenine37 in tRNA + 2 reduced [2Fe-2S] ferredoxin = S-adenosyl-L-homocysteine + L-methionine + 5′-deoxyadenosine + 2-methyladenine37 in tRNA + 2 oxidized [2Fe-2S] ferredoxin
Other name(s): RlmN; YfgB; Cfr
Systematic name: S-adenosyl-L-methionine:23S rRNA (adenine2503-C2)-methyltransferase
Comments: Contains an [4Fe-4S] cluster [2]. This enzyme is a member of the ’AdoMet radical’ (radical SAM) family. S-Adenosyl-L-methionine acts as both a radical generator and as the source of the appended methyl group. RlmN first transfers an CH2 group to a conserved cysteine (Cys355 in Escherichia coli) [6], the generated radical from a second S-adenosyl-L-methionine then attacks the methyl group, exctracting a hydrogen. The formed radical forms a covalent intermediate with the adenine group of the tRNA [9]. RlmN is an endogenous enzyme used by the cell to refine functions of the ribosome in protein synthesis [2]. The enzyme methylates adenosine by a radical mechanism with CH2 from the S-adenosyl-L-methionine and retention of the hydrogen at C-2 of adenosine2503 of 23S rRNA. It will also methylate 8-methyladenosine2503 of 23S rRNA. cf. EC 2.1.1.224 [23S rRNA (adenine2503-C8)-methyltransferase].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Toh, S.M., Xiong, L., Bae, T. and Mankin, A.S. The methyltransferase YfgB/RlmN is responsible for modification of adenosine 2503 in 23S rRNA. RNA 14 (2008) 98–106. [PMID: 18025251]
2.  Yan, F., LaMarre, J.M., Röhrich, R., Wiesner, J., Jomaa, H., Mankin, A.S. and Fujimori, D.G. RlmN and Cfr are radical SAM enzymes involved in methylation of ribosomal RNA. J. Am. Chem. Soc. 132 (2010) 3953–3964. [PMID: 20184321]
3.  Yan, F. and Fujimori, D.G. RNA methylation by radical SAM enzymes RlmN and Cfr proceeds via methylene transfer and hydride shift. Proc. Natl. Acad. Sci. USA 108 (2011) 3930–3934. [PMID: 21368151]
4.  Grove, T.L., Benner, J.S., Radle, M.I., Ahlum, J.H., Landgraf, B.J., Krebs, C. and Booker, S.J. A radically different mechanism for S-adenosylmethionine-dependent methyltransferases. Science 332 (2011) 604–607. [PMID: 21415317]
5.  Boal, A.K., Grove, T.L., McLaughlin, M.I., Yennawar, N.H., Booker, S.J. and Rosenzweig, A.C. Structural basis for methyl transfer by a radical SAM enzyme. Science 332 (2011) 1089–1092. [PMID: 21527678]
6.  Grove, T.L., Radle, M.I., Krebs, C. and Booker, S.J. Cfr and RlmN contain a single [4Fe-4S] cluster, which directs two distinct reactivities for S-adenosylmethionine: methyl transfer by SN2 displacement and radical generation. J. Am. Chem. Soc. 133 (2011) 19586–19589. [PMID: 21916495]
7.  McCusker, K.P., Medzihradszky, K.F., Shiver, A.L., Nichols, R.J., Yan, F., Maltby, D.A., Gross, C.A. and Fujimori, D.G. Covalent intermediate in the catalytic mechanism of the radical S-adenosyl-L-methionine methyl synthase RlmN trapped by mutagenesis. J. Am. Chem. Soc. 134 (2012) 18074–18081. [PMID: 23088750]
8.  Benitez-Paez, A., Villarroya, M. and Armengod, M.E. The Escherichia coli RlmN methyltransferase is a dual-specificity enzyme that modifies both rRNA and tRNA and controls translational accuracy. RNA 18 (2012) 1783–1795. [PMID: 22891362]
9.  Silakov, A., Grove, T.L., Radle, M.I., Bauerle, M.R., Green, M.T., Rosenzweig, A.C., Boal, A.K. and Booker, S.J. Characterization of a cross-linked protein-nucleic acid substrate radical in the reaction catalyzed by RlmN. J. Am. Chem. Soc. 136 (2014) 8221–8228. [PMID: 24806349]
[EC 2.1.1.192 created 2010, modified 2011, modified 2014]
 
 


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