1. Nonredox thiolation in tRNA occurring via sulfur activation by a [4Fe-4S] cluster.
- Author
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Arragain S, Bimai O, Legrand P, Caillat S, Ravanat JL, Touati N, Binet L, Atta M, Fontecave M, and Golinelli-Pimpaneau B
- Subjects
- Binding Sites, Catalysis, Cloning, Molecular, Genome, Bacterial, Iron-Sulfur Proteins chemistry, Models, Biological, Multigene Family, Oxidation-Reduction, RNA, Transfer genetics, Spectrophotometry, Ultraviolet, Sulfurtransferases genetics, Thermotoga maritima genetics, RNA Processing, Post-Transcriptional, RNA, Transfer chemistry, Sulfhydryl Compounds chemistry, Sulfur chemistry
- Abstract
Sulfur is present in several nucleosides within tRNAs. In particular, thiolation of the universally conserved methyl-uridine at position 54 stabilizes tRNAs from thermophilic bacteria and hyperthermophilic archaea and is required for growth at high temperature. The simple nonredox substitution of the C2-uridine carbonyl oxygen by sulfur is catalyzed by tRNA thiouridine synthetases called TtuA. Spectroscopic, enzymatic, and structural studies indicate that TtuA carries a catalytically essential [4Fe-4S] cluster and requires ATP for activity. A series of crystal structures shows that ( i ) the cluster is ligated by only three cysteines that are fully conserved, allowing the fourth unique iron to bind a small ligand, such as exogenous sulfide, and ( ii ) the ATP binding site, localized thanks to a protein-bound AMP molecule, a reaction product, is adjacent to the cluster. A mechanism for tRNA sulfuration is suggested, in which the unique iron of the catalytic cluster serves to bind exogenous sulfide, thus acting as a sulfur carrier., Competing Interests: The authors declare no conflict of interest.
- Published
- 2017
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