Abstract
SummaryCohesin is a conserved ring-shaped multiprotein complex that participates in chromosome segregation, DNA repair, and transcriptional regulation [1, 2]. Cohesin loading onto chromosomes universally requires the Scc2/4 “loader” complex (also called NippedBL/Mau2), mutations in which cause the developmental disorder Cornelia de Lange syndrome in humans [1–9]. Cohesin is most concentrated in the pericentromere, the region surrounding the centromere [10–15]. Enriched pericentromeric cohesin requires the Ctf19 kinetochore subcomplex in budding yeast [16–18]. Here, we uncover the spatial and temporal determinants for Scc2/4 centromere association. We demonstrate that the critical role of the Ctf19 complex is to enable Scc2/4 association with centromeres, through which cohesin loads and spreads onto the adjacent pericentromere. We show that, unexpectedly, Scc2 association with centromeres depends on cohesin itself. The absence of the Scc1/Mcd1/Rad21 cohesin subunit precludes Scc2 association with centromeres from anaphase until late G1. Expression of SCC1 is both necessary and sufficient for the binding of cohesin to its loader, the association of Scc2 with centromeres, and cohesin loading. We propose that cohesin triggers its own loading by enabling Scc2/4 to connect with chromosomal landmarks, which at centromeres are specified by the Ctf19 complex. Overall, our findings provide a paradigm for the spatial and temporal control of cohesin loading.
Highlights
Scc2 Association with Centromeres Depends on the Ctf19 Complex Cohesin is highly enriched throughout the pericentromere, yet the Scc2/4 cohesin loader shows strong enrichment only within the core w125 bp centromere [10, 19,20,21]
Even when the Ctf19 complex was purified from cells producing a version of Smc3 (Smc3E1155Q) blocked at an early step in cohesin loading [20, 23], virtually the entire kinetochore, yet only very few peptides of cohesin and its loader, were recovered (Figure S1E and Table S3)
At a site (IV-c2) directly adjacent to the CEN4-proximal lacOs, production of Scc4-LacI reproducibly increased the levels of the cohesin loader (Scc2) and restored Scc1 to close to wild-type levels in chl4D cells (Figure 1A)
Summary
Cohesin is a conserved ring-shaped multiprotein complex that participates in chromosome segregation, DNA repair, and transcriptional regulation [1, 2]. Cohesin is most concentrated in the pericentromere, the region surrounding the centromere [10,11,12,13,14,15]. Enriched pericentromeric cohesin requires the Ctf kinetochore subcomplex in budding yeast [16,17,18]. We demonstrate that the critical role of the Ctf complex is to enable Scc2/4 association with centromeres, through which cohesin loads and spreads onto the adjacent pericentromere. Scc association with centromeres depends on cohesin itself. The absence of the Scc1/Mcd1/Rad cohesin subunit precludes Scc association with centromeres from anaphase until late G1. We propose that cohesin triggers its own loading by enabling Scc2/4 to connect with chromosomal landmarks, which at centromeres are specified by the Ctf complex. Our findings provide a paradigm for the spatial and temporal control of cohesin loading
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