The <i>Saccharomyces cerevisiae TAN1</i> gene is required for <i>N</i>⁴-acetylcytidine formation in tRNA

Abstract

The biogenesis of transfer RNA is a process that requires many different factors. In this study, we describe a genetic screen aimed to identify gene products participating in this process. By screening for mutations lethal in combination with a sup61-T47:2C allele, coding for a mutant form of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{tRNA^{Ser}_{CGA}}\) \end{document} , the nonessential TAN1 gene was identified. We show that the TAN1 gene product is required for formation of the modified nucleoside N 4 -acetylcytidine (ac 4 C) in tRNA. In Saccharomyces cerevisiae , ac 4 C is present at position 12 in tRNAs specific for leucine and serine as well as in 18S ribosomal RNA. Analysis of RNA isolated from a tan1 -null mutant revealed that ac 4 C was absent in tRNA, but not rRNA. Although no tRNA acetyltransferase activity by a GST-Tan1 fusion protein was detected, a gel-shift assay revealed that Tan1p binds tRNA, suggesting a direct role in synthesis of ac 4 C 12 . The absence of the TAN1 gene in the sup61-T47:2C mutant caused a decreased level of mature \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{tRNA^{Ser}_{CGA}}\) \end{document} , indicating that ac 4 C 12 and/or Tan1p is important for tRNA stability.