Fission yeast Schizosaccharomyces pombe correctly excises a mammalian RNA transcript intervening sequence.

Study of heterologous gene expression in the budding yeast Saccharomyces cerevisiae has shown that this organism is incapable of correctly removing intervening sequences from transcripts of higher eukaryotic genes. This is probably due to the stringent requirement for the presence of a TACTAAC box close to the 3' end of the intervening sequence if splicing in S. cerevisiae is to occur. Comparison of the introns found in the fission yeast Schizosaccharomyces pombe has identified conserved sequences similar to those found in higher eukaryotes. Therefore, we have investigated whether Schiz. pombe is capable of accurately excising intervening sequences from the transcripts of higher eukarotic genes. We show here that both the 5' and 3' splice sites of the simian virus 40 (SV40) small-T antigen transcript are accurately utilized when cloned viral DNA is expressed in Schiz. pombe cells. These data suggest that Schiz. pombe may be a better model system than S. cerevisiae for the genetic study of RNA splicing and for expressing higher eukaryotic genes.