5mkp
Non redox thiolation in transfer RNAs occuring via sulfur activation by a [4Fe-4S] cluster
Structural highlights
FunctionTTUA_PYRHO Catalyzes the ATP-dependent 2-thiolation of 5-methyluridine residue at position 54 in the T loop of tRNAs, leading to 5-methyl-2-thiouridine (m(5)s(2)U or s(2)T) (PubMed:28655838). This modification allows thermal stabilization of tRNAs in thermophilic microorganisms, and is required for cell growth at high temperatures (By similarity). Can use free sulfide as sulfur source in vitro, which may be also the sulfur source in vivo (PubMed:28655838).[UniProtKB:Q72LF3][1] Publication Abstract from PubMedSulfur 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. Nonredox thiolation in tRNA occurring via sulfur activation by a [4Fe-4S] cluster.,Arragain S, Bimai O, Legrand P, Caillat S, Ravanat JL, Touati N, Binet L, Atta M, Fontecave M, Golinelli-Pimpaneau B Proc Natl Acad Sci U S A. 2017 Jul 11;114(28):7355-7360. doi:, 10.1073/pnas.1700902114. Epub 2017 Jun 27. PMID:28655838[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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