title: Assembly of the cytokinetic contractile ring from a broad band of nodes in fission yeast.
abstract: We observed live fission yeast expressing pairs of functional fluorescent fusion proteins to test the popular model that the cytokinetic contractile ring assembles from a single myosin II progenitor or a Cdc12p-Cdc15p spot. Under our conditions, the anillin-like protein Mid1p establishes a broad band of small dots or nodes in the cortex near the nucleus. These nodes mature by the addition of conventional myosin II (Myo2p, Cdc4p, and Rlc1p), IQGAP (Rng2p), pombe Cdc15 homology protein (Cdc15p), and formin (Cdc12p). The nodes coalesce laterally into a compact ring when Cdc12p and profilin Cdc3p stimulate actin polymerization. We did not observe assembly of contractile rings by extension of a leading cable from a single spot or progenitor. Arp2/3 complex and its activators accumulate in patches near the contractile ring early in anaphase B, but are not concentrated in the contractile ring and are not required for assembly of the contractile ring. Their absence delays late steps in cytokinesis, including septum formation and cell separation.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: Jian-Qiu
authors.initials: JQ
authors.lastname: Wu
authors.forename: Vladimir
authors.initials: V
authors.lastname: Sirotkin
authors.forename: David R
authors.initials: DR
authors.lastname: Kovar
authors.forename: Matthew
authors.initials: M
authors.lastname: Lord
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Beltzner
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Kuhn
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Pollard
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D048749:Cytokinesis; D008164:Luminescent Proteins / Q000378:metabolism; D008954:Models, Biological; D018995:Myosin Heavy Chains / Q000378:metabolism; D024462:Myosin Type II / Q000378:metabolism; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics; D013997:Time Factors
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D018797:Cell Cycle Proteins; D008164:Luminescent Proteins; C489694:Mid1 protein, S pombe; C110514:Myp2 protein, S pombe; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; C417034:Wsp1 protein, S pombe; C491828:myo1 protein, S pombe; C490463:rlc1 protein, S pombe; D024462:Myosin Type II; D018995:Myosin Heavy Chains