The role of novel post-translational modifications of the cohesin

Meiosis is a specialised cell division that produces gametes (e.g., egg and sperm cells) that contain only half the number of chromosomes of the parent cell. Meiosis is thus essential for all sexually reproducing organisms. Although we know many details about meiosis, we are far from a thorough understanding. Cohesin is a protein complex that has several essential roles during meiosis. Our recent analysis showed that during meiosis, methyl groups are added to the cohesin. We know from previous studies that protein methylation is an important mechanism that regulates protein function. In this project, we want to decipher the role of cohesin methylation using the fission yeast Schizosaccharomyces pombe as a model organism. We believe that this will help us understand how cohesin complex functions and provide important insights about the mechanism of chromosome segregation during meiosis.

Chromosomes are essential for living organisms because they store DNA and make it available for the cell when needed. The fission yeast Schizosaccharomyces pombe is a model unicellular organism which has been important for studying various aspects of chromosome biology. The main aim of this project was to contribute to our understanding of molecular mechanisms responsible for proper segregation of chromosomes. Our studies included one of the key chromosomal protein complexes called cohesin, as well as other proteins involved in proper segregation of chromosomes during the cell division. An important aspect of our work covered meiotic processes. Meiosis is a specialized type of cell division which produces gametes that contain only half as many of chromosomes as the parent cell (e.g., oocytes, sperm cells or spores in yeasts). Our experiments showed that cohesin that cannot be modified by methylation is not able to efficiently repair damaged chromosomal DNA. Other experiments detected nearly all proteins that are present in cells during various stages of meiosis and identified new proteins that have not been know yet. The results of this project will help us understand how cohesin and other studied proteins ensure that cells receive all required chromosomes and that they properly function.