title: The spatial segregation of pericentric cohesin and condensin in the mitotic spindle.
abstract: In mitosis, the pericentromere is organized into a spring composed of cohesin, condensin, and a rosette of intramolecular chromatin loops. Cohesin and condensin are enriched in the pericentromere, with spatially distinct patterns of localization. Using model convolution of computer simulations, we deduce the mechanistic consequences of their spatial segregation. Condensin lies proximal to the spindle axis, whereas cohesin is radially displaced from condensin and the interpolar microtubules. The histone deacetylase Sir2 is responsible for the axial position of condensin, while the radial displacement of chromatin loops dictates the position of cohesin. The heterogeneity in distribution of condensin is most accurately modeled by clusters along the spindle axis. In contrast, cohesin is evenly distributed (barrel of 500-nm width × 550-nm length). Models of cohesin gradients that decay from the centromere or sister cohesin axis, as previously suggested, do not match experimental images. The fine structures of cohesin and condensin deduced with subpixel localization accuracy reveal critical features of how these complexes mold pericentric chromatin into a functional spring.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280 Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Stephens
authors.forename: Cory W
authors.initials: CW
authors.lastname: Quammen
authors.forename: Binny
authors.initials: B
authors.lastname: Chang
authors.forename: Julian
authors.initials: J
authors.lastname: Haase
authors.forename: Russell M
authors.initials: RM
authors.lastname: Taylor
authors.forename: Kerry
authors.initials: K
authors.lastname: Bloom
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002503:Centromere / Q000235:genetics; D002843:Chromatin / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D003198:Computer Simulation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018386:Kinetochores; D008870:Microtubules; D008938:Mitosis / Q000235:genetics*; D046912:Multiprotein Complexes / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics; D056565:Sirtuin 2 / Q000235:genetics; D008941:Spindle Apparatus / Q000235:genetics*; D000097722:Cohesins
chemical_list: D000251:Adenosine Triphosphatases; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D056565:Sirtuin 2; D000097722:Cohesins; C108312:condensin complexes; C087778:SIR2 protein, S cerevisiae