title: Thio-modification of yeast cytosolic tRNA requires a ubiquitin-related system that resembles bacterial sulfur transfer systems.
abstract: The wobble uridine in yeast cytosolic tRNA(Lys2)(UUU) and tRNA(Glu3)(UUC) undergoes a thio-modification at the second position (s(2) modification) and a methoxycarbonylmethyl modification at the fifth position (mcm(5) modification). We previously demonstrated that the cytosolic and mitochondrial iron-sulfur (Fe/S) cluster assembly machineries termed CIA and ISC, including a cysteine desulfurase called Nfs1, were essential for the s(2) modification. However, the cytosolic component that directly participates in this process remains unclear. We found that ubiquitin-like protein Urm1 and ubiquitin-activating enzyme-like protein Uba4, as well as Tuc1 and Tuc2, were strictly required for the s(2) modification. The carboxyl-terminal glycine residue of Urm1 was critical for the s(2) modification, indicating direct involvement of the unique ubiquitin-related system in this process. We also demonstrated that the s(2) and mcm(5) modifications in cytosolic tRNAs influence each other's efficiency. Taken together, our data indicate that the s(2) modification of cytosolic tRNAs is a more complex process that requires additional unidentified components.
authors.affiliation: Department of Biochemistry, Osaka Medical College, 2-7 Daigaku-cho, Takatsuki 569-8686. Electronic address: med004@art.osaka-med.ac.jp.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Nakai
authors.affiliation: Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nakai
authors.affiliation: Department of Biochemistry, Osaka Medical College, 2-7 Daigaku-cho, Takatsuki 569-8686.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D024101:Mitochondrial Proteins; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012352:RNA, Transfer, Glu / Q000235:genetics / Q000378:metabolism*; D012357:RNA, Transfer, Lys; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013466:Sulfurtransferases; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*
chemical_list: D024101:Mitochondrial Proteins; D012331:RNA, Fungal; D012352:RNA, Transfer, Glu; D012357:RNA, Transfer, Lys; D029701:Saccharomyces cerevisiae Proteins; C522198:TUC1 protein, S cerevisiae; C406283:UBA4 protein, S cerevisiae; D025801:Ubiquitin; D013466:Sulfurtransferases; C115912:NFS1 protein, S cerevisiae