Abstract
The ring-shaped chromosomal cohesin complex holds sister chromatids together by topological embrace, a prerequisite for accurate chromosome segregation. Cohesin plays additional roles in genome organization, transcriptional regulation, and DNA repair. The cohesin ring includes an ABC family ATPase, but the molecular mechanism by which the ATPase contributes to cohesin function is not yet understood. In this study, we have purified budding yeast cohesin, as well as its Scc2–Scc4 cohesin loader complex, and biochemically reconstituted ATP-dependent topological cohesin loading onto DNA. Our results reproduce previous observations obtained using fission yeast cohesin, thereby establishing conserved aspects of cohesin behavior. Unexpectedly, we find that nonhydrolyzable ATP ground state mimetics ADP·BeF2, ADP·BeF3−, and ADP·AlFx, but not a hydrolysis transition state analog ADP·VO43−, support cohesin loading. The energy from nucleotide binding is sufficient to drive the DNA entry reaction into the cohesin ring. ATP hydrolysis, believed to be essential for in vivo cohesin loading, must serve a subsequent reaction step. These results provide molecular insights into cohesin function and open new experimental opportunities that the budding yeast model affords.
- Received July 30, 2018.
- Revision received October 10, 2018.
- Accepted October 10, 2018.
- © 2018 Minamino et al.
This article is available under a Creative Commons License (Attribution 4.0 International, as described at https://creativecommons.org/licenses/by/4.0/).