title: Cohesin, condensin, and the intramolecular centromere loop together generate the mitotic chromatin spring.
abstract: Sister chromatid cohesion provides the mechanistic basis, together with spindle microtubules, for generating tension between bioriented chromosomes in metaphase. Pericentric chromatin forms an intramolecular loop that protrudes bidirectionally from the sister chromatid axis. The centromere lies on the surface of the chromosome at the apex of each loop. The cohesin and condensin structural maintenance of chromosomes (SMC) protein complexes are concentrated within the pericentric chromatin, but whether they contribute to tension-generating mechanisms is not known. To understand how pericentric chromatin is packaged and resists tension, we map the position of cohesin (SMC3), condensin (SMC4), and pericentric LacO arrays within the spindle. Condensin lies proximal to the spindle axis and is responsible for axial compaction of pericentric chromatin. Cohesin is radially displaced from the spindle axis and confines pericentric chromatin. Pericentric cohesin and condensin contribute to spindle length regulation and dynamics in metaphase. Together with the intramolecular centromere loop, these SMC complexes constitute a molecular spring that balances spindle microtubule force in metaphase.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Stephens
authors.forename: Julian
authors.initials: J
authors.lastname: Haase
authors.forename: Leandra
authors.initials: L
authors.lastname: Vicci
authors.forename: Russell M
authors.initials: RM
authors.lastname: Taylor
authors.forename: Kerry
authors.initials: K
authors.lastname: Bloom
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D002503:Centromere / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D002868:Chromosomal Proteins, Non-Histone / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D008870:Microtubules / Q000502:physiology; D008938:Mitosis / Q000502:physiology*; D008968:Molecular Conformation; D046912:Multiprotein Complexes / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D004718:Saccharomycetales / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; 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; D000097722:Cohesins; C108312:condensin complexes