title: Mechanism of cytokinetic contractile ring constriction in fission yeast.
abstract: Cytokinesis involves constriction of a contractile actomyosin ring. The mechanisms generating ring tension and setting the constriction rate remain unknown because the organization of the ring is poorly characterized, its tension was rarely measured, and constriction is coupled to other processes. To isolate ring mechanisms, we studied fission yeast protoplasts, in which constriction occurs without the cell wall. Exploiting the absence of cell wall and actin cortex, we measured ring tension and imaged ring organization, which was dynamic and disordered. Computer simulations based on the amounts and biochemical properties of the key proteins showed that they spontaneously self-organize into a tension-generating bundle. Together with rapid component turnover, the self-organization mechanism continuously reassembles and remodels the constricting ring. Ring constriction depended on cell shape, revealing that the ring operates close to conditions of isometric tension. Thus, the fission yeast ring sets its own tension, but other processes set the constriction rate.
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Stachowiak
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Laplante
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Harvey F
authors.initials: HF
authors.lastname: Chin
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Boris
authors.initials: B
authors.lastname: Guirao
authors.affiliation: Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, CT 06520, USA; Nanobiology Institute, Yale University, New Haven, CT 06520, USA.
authors.forename: Erdem
authors.initials: E
authors.lastname: Karatekin
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA; Department of Cell Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Pollard
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027, USA. Electronic address: bo8@columbia.edu.
authors.forename: Ben
authors.initials: B
authors.lastname: O'Shaughnessy
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism*; D003198:Computer Simulation; D048749:Cytokinesis / Q000502:physiology*; D024462:Myosin Type II / Q000378:metabolism; D058105:Polymerization; D012568:Schizosaccharomyces / Q000166:cytology / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism*
chemical_list: D029702:Schizosaccharomyces pombe Proteins; D000205:Actomyosin; D024462:Myosin Type II