Cells contain molecular machines consisting of protein complexes that convert chemical energy into mechanical work. These machines use the work to help either assemble or disassemble cellular structures during vital cell processes. Understanding the mechanisms of action of these biological machines and their relationship with conformational changes in their substrates are among the challenges of modern molecular biology. This project uses computational modeling at multiple scales to elucidate how a class of molecular machines associated with microtubules accomplishes the severing of this largest structure in the cytoskeleton, whose dynamic organization and rearrangement is an essential process of cell division, motility, and development. This research will address a critical gap in our understanding of the dynamic properties of microtubules and their complexes with microtubule associated proteins undergoing wear and their dependence on the magnitude and geometry of mechanical input and will lead to a better understanding of how molecular machines work. The project will provide education and training of undergraduate and graduate students in computational biophysical chemistry by involving them in interdisciplinary scientific projects and increase the participation of groups underrepresented in science through the outreach at local Cincinnati Public School and through research experience opportunities for freshmen students participating in the "Women in Science and Engineering" program at the University of Cincinnati. The results of the project will be disseminated to the public by the investigator, postdoc, and students through publications, conference presentations, and visits to local schools.
This project will elucidate the major remodeling action of microtubules performed by severing enzymes from the ATPases Associated with various cellular Activities (AAA+) family. The multiscale simulations will determine molecular and thermodynamic parameters that characterize the breaking of a microtubule filament according to the proposed severing mechanisms. Because the action of AAA+ proteins is known to involve the application of pulling forces on their substrate proteins, in this project simulations that can reach the long time and length-scales required to follow the action of severing enzymes, primarily katanin in its hexameric functional states, will be complemented by experiments conducted by collaborators to extract markers of the unfoldase action on microtubules. Furthermore, the contribution of allosteric transitions between the active states of these hexameric enzymes to microtubule disassembly will be established. The combination of coarse-grained simulations and experiments will ultimately provide quantitative insight into the power stroke action of severing enzymes.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
