title: Condensin, chromatin crossbarring and chromosome condensation.
abstract: The processes underlying the large-scale reorganisation of chromatin in mitosis that form compact mitotic chromosomes and ensure the fidelity of chromosome segregation during cell division still remain obscure. The chromosomal condensin complex is a major molecular effector of chromosome condensation and segregation in diverse organisms ranging from bacteria to humans. Condensin is a large, evolutionarily conserved, multisubunit protein assembly composed of dimers of the structural maintenance of chromosomes (SMC) family of ATPases, clasped into topologically closed rings by accessory subunits. Condensin binds to DNA dynamically, in a poorly understood cycle of ATP-modulated conformational changes, and exhibits the ability to positively supercoil DNA. During mitosis, condensin is phosphorylated by the cyclin-dependent kinase (CDK), Polo and Aurora B kinases in a manner that correlates with changes in its localisation, dynamics and supercoiling activity. Here we review the reported architecture, biochemical activities and regulators of condensin. We compare models of bacterial and eukaryotic condensins in order to uncover conserved mechanistic principles of condensin action and to propose a model for mitotic chromosome condensation.
authors.affiliation: Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
authors.forename: Rahul
authors.initials: R
authors.lastname: Thadani
authors.forename: Frank
authors.initials: F
authors.lastname: Uhlmann
authors.forename: Sebastian
authors.initials: S
authors.lastname: Heeger
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002453:Cell Cycle; D002843:Chromatin / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D015394:Molecular Structure; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C108312:condensin complexes; D000251:Adenosine Triphosphatases