The Specificities of Four Yeast Dihydrouridine Synthases for Cytoplasmic tRNAs[boxs]

• Published in: The Journal of biological chemistry Vol. 279; no. 17; pp. 17850 - 17860
• Main Authors: Xing, Feng, Hiley, Shawna L., Hughes, Timothy R., Phizicky, Eric M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 23.04.2004; American Society for Biochemistry and Molecular Biology
• Subjects: Chromatography, High Pressure Liquid; Cytoplasm - metabolism; DNA Primers - chemistry; Down-Regulation; Models, Chemical; Nucleic Acid Hybridization; Oligonucleotide Array Sequence Analysis; Oxidoreductases - chemistry; RNA - chemistry; RNA, Transfer - chemistry; RNA, Transfer - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Temperature; Up-Regulation; Uridine - chemistry
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M401221200

Dihydrouridine is a highly abundant modified nucleoside found widely in tRNAs of eubacteria, eukaryotes, and some archaea. In cytoplasmic tRNA of Saccharomyces cerevisiae, dihydrouridine occurs exclusively at positions 16, 17, 20, 20A, 20B, and 47. Here we show that the known dihydrouridine synthases Dus1p and Dus2p and two previously uncharacterized homologs, Dus3p (encoded by YLR401c) and Dus4p (YLR405w), are required for all of the dihydrouridine modification of cytoplasmic tRNAs in S. cerevisiae. We have mapped the in vivo position specificity of the four Dus proteins, by three complementary approaches: determination of the molar ratio of dihydrouridine in purified tRNAs from different dus mutants; microarray analysis of a large number of tRNAs based on differential hybridization of uridineand dihydrouridine-containing tRNAs to the complementary oligonucleotides; and the development and use of a novel dihydrouridine mapping technique, employing primer extension. We show that each of the four Dus proteins has a distinct position specificity: Dus1p for U16 and U17, Dus2p for U20, Dus3p for U47, and Dus4p for U20a and U20b.