4pjw
From Proteopedia
crystal structure of human Stromal Antigen 2 (SA2) in complex with Sister Chromatid Cohesion protein 1 (Scc1), with bound MES
Structural highlights
Disease[RAD21_HUMAN] Cornelia de Lange syndrome. The disease is caused by mutations affecting the gene represented in this entry.[1] Function[STAG2_HUMAN] Component of cohesin complex, a complex required for the cohesion of sister chromatids after DNA replication. The cohesin complex apparently forms a large proteinaceous ring within which sister chromatids can be trapped. At anaphase, the complex is cleaved and dissociates from chromatin, allowing sister chromatids to segregate. The cohesin complex may also play a role in spindle pole assembly during mitosis.[2] [RAD21_HUMAN] Cleavable component of the cohesin complex, involved in chromosome cohesion during cell cycle, in DNA repair, and in apoptosis. The cohesin complex is required for the cohesion of sister chromatids after DNA replication. The cohesin complex apparently forms a large proteinaceous ring within which sister chromatids can be trapped. At metaphase-anaphase transition, this protein is cleaved by separase/ESPL1 and dissociates from chromatin, allowing sister chromatids to segregate. The cohesin complex may also play a role in spindle pole assembly during mitosis. Also plays a role in apoptosis, via its cleavage by caspase-3/CASP3 or caspase-7/CASP7 during early steps of apoptosis: the C-terminal 64 kDa cleavage product may act as a nuclear signal to initiate cytoplasmic events involved in the apoptotic pathway.[3] [4] Publication Abstract from PubMedOrderly termination of sister-chromatid cohesion during mitosis is critical for accurate chromosome segregation. During prophase, mitotic kinases phosphorylate cohesin and its protector sororin, triggering Wapl-dependent cohesin release from chromosome arms. The shugoshin (Sgo1)-PP2A complex protects centromeric cohesin until its cleavage by separase at anaphase onset. Here, we report the crystal structure of a human cohesin subcomplex comprising SA2 and Scc1. Multiple HEAT repeats of SA2 form a dragon-shaped structure. Scc1 makes extensive contacts with SA2, with one binding hotspot. Sgo1 and Wapl compete for binding to a conserved site on SA2-Scc1. At this site, mutations of SA2 residues that disrupt Wapl binding bypass the Sgo1 requirement in cohesion protection. Thus, in addition to recruiting PP2A to dephosphorylate cohesin and sororin, Sgo1 physically shields cohesin from Wapl. This unexpected, direct antagonism between Sgo1 and Wapl augments centromeric cohesion protection. Structure of cohesin subcomplex pinpoints direct shugoshin-Wapl antagonism in centromeric cohesion.,Hara K, Zheng G, Qu Q, Liu H, Ouyang Z, Chen Z, Tomchick DR, Yu H Nat Struct Mol Biol. 2014 Aug 31. doi: 10.1038/nsmb.2880. PMID:25173175[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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