Michael Brown ’22
Major: Molecular Biology
Faculty Collaborators: Jennifer Garcia, Molecular Biology; Sara Hanson, Molecular Biology
Understanding centromere composition in organisms is integral to our understanding of cell development and chromosomal stability. Without proper centromere composition, faithful segregation of chromosomes cannot occur, hence making cells less viable over time. To investigate how centromere composition is established, we examined the genomes of 28 yeast species, many with evolutionarily distinct centromeres, for 8 genes important in centromere composition. Within centromeres, a histone variant in yeast, Cse4, (e.g. CENP-A in higher eukaryotes), has been shown to act as the platform for proteins necessary for chromosome segregation to occur. In some species of yeast, Scm3 has been observed to incorporate Cse4 into the centromeric region of the genome while other proteins have been shown in other yeasts to remove Cse4 from non-centromeric regions. We found that Cse4is less conserved over the 28 species, implying that in some yeast Cse4 is not necessary for centromere function. Scm3 is well conserved implying that Scm3 is necessary for yeast and may perform some other function outside of depositing Cse4. Finally, Psh1, which can remove Cse4,is somewhat conserved throughout yeast indicating that there may be other tools involved preventing Cse4 mis-localization. Our research shows that centromere composition in yeast can evolve complexity despite its essential role in promoting chromosome segregation and point towards future avenues of research.