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Common thiolation mechanism in the biosynthesis of tRNA thiouridine and sulphur‐containing cofactors
Author(s) -
Shigi Naoki,
Sakaguchi Yuriko,
Asai Shinichi,
Suzuki Tsutomu,
Watanabe Kimitsuna
Publication year - 2008
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2008.246
Subject(s) - biology , transfer rna , cofactor , biosynthesis , sulfur , biochemistry , mechanism (biology) , enzyme , gene , rna , chemistry , philosophy , organic chemistry , epistemology
2‐Thioribothymidine (s 2 T), a modified uridine, is found at position 54 in transfer RNAs (tRNAs) from several thermophiles; s 2 T stabilizes the L‐shaped structure of tRNA and is essential for growth at higher temperatures. Here, we identified an ATPase (tRNA‐two‐thiouridine C, TtuC) required for the 2‐thiolation of s 2 T in Thermus thermophilus and examined in vitro s 2 T formation by TtuC and previously identified s 2 T‐biosynthetic proteins (TtuA, TtuB, and cysteine desulphurases). The C‐terminal glycine of TtuB is first activated as an acyl‐adenylate by TtuC and then thiocarboxylated by cysteine desulphurases. The sulphur atom of thiocarboxylated TtuB is transferred to tRNA by TtuA. In a ttuC mutant of T. thermophilus , not only s 2 T, but also molybdenum cofactor and thiamin were not synthesized, suggesting that TtuC is shared among these biosynthetic pathways. Furthermore, we found that a TtuB—TtuC thioester was formed in vitro , which was similar to the ubiquitin‐E1 thioester, a key intermediate in the ubiquitin system. The results are discussed in relation to the mechanism and evolution of the eukaryotic ubiquitin system.