Presentation description

Correct chromosome segregation relies on the bioriented interaction between kinetochore proteins and microtubules from opposite spindle poles. Stu2 is thought to play an essential role in this process, depending on its TOG domains and basic linker (BL). Our research focused on identifying a key regulatory interaction between these regions, as initial observations showed that cells with a TOG2∆ were sick, but this sickness was rescued by further deleting the BL, suggesting regulation of Stu2's BL by its TOG2 domain. We investigated the interaction between TOG2 and BL and the reasoning behind the TOG2∆ sickness. Our first hypothesis was that without TOG2, the positively charged BL binds too strongly to the negatively charged microtubules, sequestering Stu2 away from the kinetochore. Our second hypothesis is based on an alphafold structural prediction which suggests an interaction between Stu2 and the outer kinetochore Ndc80 complex, causing defects in accurate kinetochore biorientation and cell sickness if not regulated by TOG2. Our experiments did not find an interaction region on TOG2 with the BL and further work needs to be done. Furthermore, we rejected our first hypothesis as there was no difference in Stu2 levels at the kinetochore between WT and TOG2∆ cells. However, we found a significant drop in the percentage of bioriented kinetochores in TOG2∆ cells compared to WT cells which was rescued in TOG2∆ BL∆ mutants, supporting our second hypothesis that irregular Stu2 interaction with the Ndc80 complex may cause sickness. Since these protein interactions also likely occur in human cells, our research allows us to gain insight on the vital mechanisms of our cells, in order to further investigate and resolve human diseases resulting from incorrect cell division.