The Saccharomyces cerevisiae TAN1 gene is required for N⁴-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 , the nonessential TAN1 gene was identified. We show that the TAN1 gene product is required for formation of the modified nucleoside N⁴-acetylcytidine (ac⁴C) in tRNA. In Saccharomyces cerevisiae, ac⁴C 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 ac⁴C 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 ac⁴C₁₂. The absence of the TAN1 gene in the sup61-T47:2C mutant caused a decreased level of mature , indicating that ac⁴C₁₂ and/or Tan1p is important for tRNA stability.

Keywords

• N4-acetylcytidine
• YGL232w
• sup61
• tRNA maturation
• tRNA modification