期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：45
页码：12703-12708
DOI：10.1073/pnas.1615732113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The sulfur-containing nucleosides in transfer RNA (tRNAs) are present in all three domains of life; they have critical functions for accurate and efficient translation, such as tRNA structure stabilization and proper codon recognition. The tRNA modification enzymes ThiI (in bacteria and archaea) and Ncs6 (in archaea and eukaryotic cytosols) catalyze the formation of 4-thiouridine (s4U) and 2-thiouridine (s2U), respectively. The ThiI homologs were proposed to transfer sulfur via cysteine persulfide enzyme adducts, whereas the reaction mechanism of Ncs6 remains unknown. Here we show that ThiI from the archaeon Methanococcus maripaludis contains a [3Fe-4S] cluster that is essential for its tRNA thiolation activity. Furthermore, the archaeal and eukaryotic Ncs6 homologs as well as phosphoseryl-tRNA (Sep-tRNA):Cys-tRNA synthase (SepCysS), which catalyzes the Sep-tRNA to Cys-tRNA conversion in methanogens, also possess a [3Fe-4S] cluster similar to the methanogenic archaeal ThiI. These results suggest that the diverse tRNA thiolation processes in archaea and eukaryotic cytosols share a common mechanism dependent on a [3Fe-4S] cluster for sulfur transfer.
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