PMID:15339930
| Citation |
Pierrel, F, Douki, T, Fontecave, M and Atta, M (2004) MiaB protein is a bifunctional radical-S-adenosylmethionine enzyme involved in thiolation and methylation of tRNA. J. Biol. Chem. 279:47555-63 |
|---|---|
| Abstract |
The last biosynthetic step for 2-methylthio-N(6)-isopentenyl-adenosine (ms(2)i(6)A), present at position 37 in some tRNAs, consists of the methylthiolation of the isopentenyl-adenosine (i(6)A) precursor. In this work we have reconstituted in vitro the conversion of i(6)A to ms(2)i(6)A within a tRNA substrate using the iron-sulfur MiaB protein, S-adenosylmethionine (AdoMet), and a reducing agent. We show that a synthetic i(6)A-containing RNA corresponding to the anticodon stem loop of tRNA(Phe) is also a substrate. This study demonstrates that MiaB protein is a bifunctional system, involved in both thiolation and methylation of i(6)A. In this process, one molecule of AdoMet is converted to 5'-deoxyadenosine, probably through reductive cleavage and intermediate formation ofa5'-deoxyadenosyl radical as observed in other "Radical-AdoMet" enzymes, and a second molecule of AdoMet is used as a methyl donor as shown by labeling experiments. The origin of the sulfur atom is discussed. |
| Links |
PubMed Online version:10.1074/jbc.M408562200 |
| Keywords |
Adenosine/chemistry; Adenosine/metabolism; Animals; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Molecular Structure; Nucleic Acid Conformation; RNA, Transfer/chemistry; RNA, Transfer/genetics; RNA, Transfer/metabolism; S-Adenosylmethionine/metabolism; Sulfurtransferases/genetics; Sulfurtransferases/metabolism; Thermotoga maritima/metabolism |
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