Abstract
The cohesin ring complex is required for numerous chromosomal transactions including sister chromatid cohesion, DNA damage repair and transcriptional regulation. How cohesin engages its chromatin substrate has remained an unresolved question. We show here, by determining a crystal structure of the budding yeast cohesin HEAT-repeat subunit Scc3 bound to a fragment of the Scc1 kleisin subunit and DNA, that Scc3 and Scc1 form a composite DNA interaction module. The Scc3-Scc1 subcomplex engages double-stranded DNA through a conserved, positively charged surface. We demonstrate that this conserved domain is required for DNA binding by Scc3-Scc1 in vitro, as well as for the enrichment of cohesin on chromosomes and for cell viability. These findings suggest that the Scc3-Scc1 DNA-binding interface plays a central role in the recruitment of cohesin complexes to chromosomes and therefore for cohesin to faithfully execute its functions during cell division.
Highlights
To ensure that each daughter cell receives an equal complement of genetic information, cognate chromatids are paired through replication-coupled sister chromatid cohesion
The chromosomal addresses of cohesin loading are determined by the Scc2-Scc4 complex, which is enriched at centromeres via direct contacts with kinetochore proteins and promotes DNA-stimulated ATP hydrolysis by the Smc1-Smc3 ATPase heads to drive chromatin entrapment (Ciosk et al, 2000; Hinshaw et al, 2017; Murayama and Uhlmann, 2014)
We produced an Smc1Smc3 hinge heterodimer, Pds5 bound to a Scc1 fragment (Muir et al, 2016) as a full-length (Pds5fl) or truncated variant (Pds5T), as well as Wapl as full-length (Waplfl) or truncated variants (WaplC; Figure 1—figure supplement 1)
Summary
To ensure that each daughter cell receives an equal complement of genetic information, cognate chromatids are paired through replication-coupled sister chromatid cohesion. Cohesin complexes form tripartite rings, comprising Smc1-Smc and the kleisin subunit Scc, that are proposed to topologically entrap sister DNA molecules (Gligoris et al, 2014; Nasmyth and Haering, 2009). Dynamic release of DNA from the ring is achieved either by the proteolytic cleavage of the Scc kleisin subunit by separase protease (Uhlmann et al, 2000), or by the opening of an ‘exit gate’ formed at the Scc and Smc interface. Release of the latter is inhibited by Smc acetylation and is controlled by the accessory
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