title: A topological interaction between cohesin rings and a circular minichromosome.
abstract: Sister chromatid cohesion depends on a multiprotein cohesin complex containing two SMC subunits, Smc1 and Smc3, that dimerize to form V-shaped molecules with ABC-like ATPase heads at the tips of their two arms. Cohesin's Smc1 and Smc3 "heads" are connected by an alpha kleisin subunit called Scc1, forming a tripartite ring with a diameter around 40 nm. We show here that some cohesin remains tightly bound to circular minichromosomes after their purification from yeast cells and that cleavage either of cohesin's ring or of the minichromosome's DNA destroys their association. This suggests that the stable association between cohesin and chromatin detected here is topological rather than physical, which is consistent with the notion that DNA is trapped inside cohesin rings.
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: Dmitri
authors.initials: D
authors.lastname: Ivanov
authors.forename: Kim
authors.initials: K
authors.lastname: Nasmyth
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002842:Chromatids / Q000502:physiology; D002868:Chromosomal Proteins, Non-Histone; D023902:Chromosome Pairing / Q000502:physiology; D015825:Chromosomes, Fungal / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004270:DNA, Circular / Q000378:metabolism*; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D010750:Phosphoproteins; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000166:cytology; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004247:DNA; D004270:DNA, Circular; D005656:Fungal Proteins; D009687:Nuclear Proteins; D009707:Nucleosomes; D010750:Phosphoproteins; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins; C490529:MCD1 protein, S cerevisiae