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Mol. Cell. Biol. doi:10.1128/MCB.01321-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Thio modification of yeast cytosolic tRNA is an iron-sulfur protein-dependent pathway

Department of Biochemistry, Osaka Medical College, 2-7 Daigakumachi, Takatsuki 569-8686, Japan; Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita 565-0871, Japan; Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, D-35033 Marburg, Germany; and Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

^* To whom correspondence should be addressed. Email: med004{at}art.osaka-med.ac.jp. hayashi{at}art.osaka-med.ac.jp.

	Abstract

Defects in yeast cysteine desulfurase, Nfs1 cause a severe impairment in 2-thio modification of uridine of the mitochondrial (mt-) tRNAs and the cytosolic (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 biosynthesis of Fe/S clusters is a prerequisite for the 2-thio modification of tRNAs in both subcellular compartments of yeast cells. To elucidate this question, we asked if mitochondrial ISC and/or cytosolic CIA components except Nfs1 would be involved in 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 to the 2-thio modification of the cytosolic tRNAs but not of the mitochondrial tRNAs while mitochondrial Nfs1 is required for both 2-thio modifications. These results clearly indicate that the 2-thio modification of cytosolic tRNAs is Fe/S protein-dependent and thus requires both CIA and ISC machineries but that of mitochondrial tRNAs is Fe/S cluster-independent and does not require key mitochondrial ISC components except Nfs1.

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• Marelja, Z., Stocklein, W., Nimtz, M., Leimkuhler, S. (2008). A Novel Role for Human Nfs1 in the Cytoplasm: Nfs1 ACTS AS A SULFUR DONOR FOR MOCS3, A PROTEIN INVOLVED IN MOLYBDENUM COFACTOR BIOSYNTHESIS. J. Biol. Chem. 283: 25178-25185 [Abstract] [Full Text]