title: Nonsense suppression in Schizosaccharomyces pombe: the S. pombe Sup3-e tRNASerUGA gene is active in S. cerevisiae.
abstract: The gene encoding the efficient UGA suppressor sup3-e of Schizosaccharomyces pombe was isolated by in vivo transformation of Saccharomyces cerevisiae UGA mutants with S. pombe sup3-e DNA. DNA from a clone bank of EcoRI fragments from a S. pombe sup3-e strain in the hybrid yeast vector YRp17 was used to transform the S. cerevisiae multiple auxotroph his4-260 leu2-2 trp1-1 to prototrophy. Transformants were isolated at a low frequency; they lost the ability to grow in minimal medium after passaging in non-selective media. This suggested the presence of the suppressor gene on the non-integrative plasmid. Plasmid DNA, isolated from the transformed S. cerevisiae cells and subsequently amplified in E. coli, transformed S. cerevisiae his4-260 leu2-2 trp1-1 to prototrophy. In this way a 2.4 kb S. pombe DNA fragment carrying the sup3-e gene was isolated. Sequence analysis revealed the presence of two tRNA coding regions separated by a spacer of only seven nucleotides. The sup3-e tRNASerUGA tRNA gene is followed by a sequence coding for the initiator tRNAMet. The transformation results demonstrate that the cloned S. pombe UGA suppressor is active in S. cerevisiae UGA mutant strains.
mesh_terms: D001203:Ascomycota / Q000235:genetics*; D001483:Base Sequence; D005796:Genes; D010957:Plasmids; D012343:RNA, Transfer / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics*; D012694:Serine; D013329:Structure-Activity Relationship; D013489:Suppression, Genetic; D014170:Transformation, Genetic
chemical_list: D012694:Serine; D012343:RNA, Transfer