Thio modification of yeast cytosolic tRNA is an iron-sulfur protein-dependent pathway.
Defects in the yeast cysteine desulfurase Nfs1 cause a severe impairment in the 2-thio modification of uridine of mitochondrial tRNAs (mt-tRNAs) and cytosolic tRNAs (cy-tRNAs). Nfs1 can also provide the sulfur atoms of the iron-sulfur (Fe/S) clusters generated by the mitochondrial and cytosolic Fe/S cluster assembly machineries, termed ISC and CIA, respectively. Therefore, a key question remains as to whether the biosynthesis of Fe/S clusters is a prerequisite for the 2-thio modification of the tRNAs in both of the subcellular compartments of yeast cells. To elucidate this question, we asked whether mitochondrial ISC and/or cytosolic CIA components besides Nfs1 were involved in the 2-thio modification of these tRNAs. We demonstrate here that the three CIA components, Cfd1, Nbp35, and Cia1, are required for the 2-thio modification of cy-tRNAs but not of mt-tRNAs. Interestingly, the mitochondrial scaffold proteins Isu1 and Isu2 are required for the 2-thio modification of the cy-tRNAs but not of the mt-tRNAs, while mitochondrial Nfs1 is required for both 2-thio modifications. These results clearly indicate that the 2-thio modification of cy-tRNAs is Fe/S protein dependent and thus requires both CIA and ISC machineries but that of mt-tRNAs is Fe/S cluster independent and does not require key mitochondrial ISC components except for Nfs1.
Nakai
Yumi
Y
Department of Biochemistry, Osaka Medical College, 2-7 Daigakumachi, Takatsuki 569-8686, Japan.
Nakai
Masato
M
Lill
Roland
R
Suzuki
Tsutomu
T
Hayashi
Hideyuki
H
D003600:Cytosol / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D012357:RNA, Transfer, Lys / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*
D007506:Iron-Sulfur Proteins; D024101:Mitochondrial Proteins; D012357:RNA, Transfer, Lys; D029701:Saccharomyces cerevisiae Proteins; D013455:Sulfur; D012343:RNA, Transfer