Abstract
Polypeptone is widely excluded from Schizosaccharomyces pombe growth medium. However, the reasons why polypeptone should be avoided have not been documented. Polypeptone dramatically induced cell lysis in the ura4 deletion mutant when cells approached the stationary growth phase, and this phenotype was suppressed by supplementation of uracil. To determine the specificity of this cell lysis phenotype, we created deletion mutants of other genes involved in de novo biosynthesis of uridine monophosphate (ura1, ura2, ura3, and ura5). Cell lysis was not observed in these gene deletion mutants. In addition, concomitant disruption of ura1, ura2, ura3, or ura5 in the ura4 deletion mutant suppressed cell lysis, indicating that cell lysis induced by polypeptone is specific to the ura4 deletion mutant. Furthermore, cell lysis was also suppressed when the gene involved in coenzyme Q biosynthesis was deleted. This is likely because Ura3 requires coenzyme Q for its activity. The ura4 deletion mutant was sensitive to zymolyase, which mainly degrades (1,3)-beta-D glucan, when grown in the presence of polypeptone, and cell lysis was suppressed by the osmotic stabiliser, sorbitol. Finally, the induction of cell lysis in the ura4 deletion mutant was due to the accumulation of orotidine-5-monophosphate. Cell wall integrity was dramatically impaired in the ura4 deletion mutant when grown in the presence of polypeptone. Because ura4 is widely used as a selection marker in S. pombe, caution needs to be taken when evaluating phenotypes of ura4 mutants.
Highlights
The fission yeast, Schizosaccharomyces pombe, is a eukaryotic model organism used to study a wide range of molecular and cellular biological processes, including cell cycle regulation, signal transduction, cell polarity control, and chromatin structure [1,2,3]
We report the ura4 deletion strains of S. pombe and S. japonicus undergo dramatic cell lysis when grown on media containing polypeptone or tryptone
The lysis phenotype of the S. pombe ura4 deletion mutant was suppressed by the expression of ura4 or S. cerevisiae URA3, or the addition of uracil to the media
Summary
The fission yeast, Schizosaccharomyces pombe, is a eukaryotic model organism used to study a wide range of molecular and cellular biological processes, including cell cycle regulation, signal transduction, cell polarity control, and chromatin structure [1,2,3]. S. pombe is used to study the mechanisms responsible for controlling cell wall synthesis and cellular morphogenesis [4]. The composition of the media on which S. pombe is grown is an important factor that needs to be considered during phenotypic analysis. S. pombe is commonly grown on the minimum medium, EMM, and the rich medium, YE [5]. Growth media commonly used for S. cerevisiae, such as YPD that contains polypeptone, and SD that contains a nitrogen base, are not widely used to grow S. pombe. This is because many researchers have observed that S. pombe grown on these media can exhibit unexpected and unwanted alterations in the phenotypes of interest. Polypeptone in YPD media is generally considered to be responsible for these effects, the reasons for this have not been thoroughly investigated
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