Structure and stability of cohesin's Smc1-kleisin interaction.
A multisubunit complex called cohesin forms a huge ring structure that mediates sister chromatid cohesion, possibly by entrapping sister DNAs following replication. Cohesin's kleisin subunit Scc1 completes the ring, connecting the ABC-like ATPase heads of a V-shaped Smc1/3 heterodimer. Proteolytic cleavage of Scc1 by separase triggers sister chromatid disjunction, presumably ... by breaking the Scc1 bridge. One half of the SMC-kleisin bridge is revealed here by a crystal structure of Smc1's ATPase complexed with Scc1's C-terminal domain. The latter forms a winged helix that binds a pair of beta strands in Smc1's ATPase head. Mutation of conserved residues within the contact interface destroys Scc1's interaction with Smc1/3 heterodimers and eliminates cohesin function. Interaction of Scc1's N terminus with Smc3 depends on prior C terminus connection with Smc1. There is little or no turnover of Smc1-Scc1 interactions within cohesin complexes in vivo because expression of noncleavable Scc1 after DNA replication does not hinder anaphase.
Mesh Terms:
Adenosine Triphosphatases, Baculoviridae, Binding Sites, Cell Cycle Proteins, Chromatids, Chromosomal Proteins, Non-Histone, Crystallography, X-Ray, DNA Mutational Analysis, Dimerization, Fungal Proteins, G1 Phase, Models, Molecular, Mutation, Nuclear Proteins, Protein Structure, Tertiary, Protein Subunits, Saccharomyces cerevisiae Proteins
Adenosine Triphosphatases, Baculoviridae, Binding Sites, Cell Cycle Proteins, Chromatids, Chromosomal Proteins, Non-Histone, Crystallography, X-Ray, DNA Mutational Analysis, Dimerization, Fungal Proteins, G1 Phase, Models, Molecular, Mutation, Nuclear Proteins, Protein Structure, Tertiary, Protein Subunits, Saccharomyces cerevisiae Proteins
Mol. Cell
Date: Sep. 24, 2004
PubMed ID: 15383284
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