10779/crick.12652334.v1 William CH Chao William CH Chao Yasuto Murayama Yasuto Murayama Sofía Muñoz Sofía Muñoz Alessandro Costa Alessandro Costa Frank Uhlmann Frank Uhlmann Martin R Singleton Martin R Singleton Structural studies reveal the functional modularity of the Scc2-Scc4 cohesin loader The Francis Crick Institute 2020 Ascomycota Chromosomal Proteins, Non-Histone Fungal Proteins Protein Structure, Quaternary Protein Structure, Secondary Protein Structure, Tertiary Costa Uhlmann Singleton SB-ack EM-ack PRT-ack 0601 Biochemistry and Cell Biology 2020-07-14 12:54:02 Journal contribution https://crick.figshare.com/articles/journal_contribution/Structural_studies_reveal_the_functional_modularity_of_the_Scc2-Scc4_cohesin_loader/12652334 The remarkable accuracy of eukaryotic cell division is partly maintained by the cohesin complex acting as a molecular glue to prevent premature sister chromatid separation. The loading of cohesin onto chromosomes is catalyzed by the Scc2-Scc4 loader complex. Here, we report the crystal structure of Scc4 bound to the N terminus of Scc2 and show that Scc4 is a tetratricopeptide repeat (TPR) superhelix. The Scc2 N terminus adopts an extended conformation and is entrapped by the core of the Scc4 superhelix. Electron microscopy (EM) analysis reveals that the Scc2-Scc4 loader complex comprises three domains: a head, body, and hook. Deletion studies unambiguously assign the Scc2N-Scc4 as the globular head domain, whereas in vitro cohesin loading assays show that the central body and the hook domains are sufficient to catalyze cohesin loading onto circular DNA, but not chromatinized DNA in vivo, suggesting a possible role for Scc4 as a chromatin adaptor.