Analysis of the S. pombe meiotic proteome reveals a switch from anabolic to catabolic processes and extensive post-transcriptional regulation

Meiotic progression in S. pombe is regulated by stage-specific gene expression and translation, changes in RNA stability, expression of anti-sense transcripts and targetted proteolysis of regulatory proteins. We have used SILAC labelling to examine the relative levels of proteins in diploid S. pombe cells during meiosis. Among the 3268 proteins quantified at all time points, the level of 880 proteins changed at least two-fold; the majority of proteins showed a stepwise increase or decrease during the meiotic divisions, while some changed transiently. Overall, we observed a reduction in proteins involved in anabolism and an increase in proteins involved in catabolism. We also saw an increase in the level of proteins of the ESCRT-III complex and revealed a role for ESCRT-III components in chromosome segregation and spore formation. Correlation with studies of meiotic gene expression and ribosome occupancy reveals that many of the changes in steady state protein levels are post-transcriptional