Presenter(s): L. Gomez Gomez
Faculty Mentor(s): Kirstin Sterner & Emily Beck
Poster 52
Session: Sciences
Chromosomal centromeres play a critical role in the process of cell division. Centromeres act as binding sites for microtubules that pull chromosomes apart during mitosis and meiosis. Despite this conserved function, the centromeres themselves can vary in size and sequence content between species. Rapid evolution in these regions can also drive rapid evolution in centromere- associated proteins. Previous work has suggested these rapid changes are likely to accumulate in one of two essential centromere components; either CENP-A or CENP-C. Through compensatory coevolution, positive selection can subsequently cascade into other essential protein complexes resulting in hybrid incompatibility. Cascading selection from the centromere to CENP-A was previously reported in Drosophila by Beck et al. 2015 demonstrating the extension of positive selection to the essential Condensin I complex (SMC2, SMC4, NCAPD2, NCAPG, NCAPH orthologs). To test if kinetochore-associated proteins evolve rapidly in other animals, we examined the sequence of CENP-A and CENP-C and their associated protein complexes, Condensin I and Mis12 (DSN1, MIS12, NSL1, PMF1) respectively, across primates. Sequences were mined from publicly available genomes (21-25 individual species per gene), aligned using Clustal-Omega and manually checked in Mesquite to ensure that protein-coding sequences conformed to codon boundaries. We then used the codeml (PAML) to test for positive selection. Our preliminary data suggests CENP-C may be evolving rapidly showing evidence of positive selection in components of Condensin1 and Mis12 complexes. This finding supports the centromere-drive hypothesis, which suggests the presence of an evolutionary tug-of-war between centromeric DNA and centromere-associated proteins that may shape karyotype evolution.