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Curr Biol. 2015 Aug 3;25(15):1955-65. doi: 10.1016/j.cub.2015.06.018. Epub 2015 Jul 2.

Three myosins contribute uniquely to the assembly and constriction of the fission yeast cytokinetic contractile ring.

Author information

1
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
2
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA; Nanobiology Institute, Yale University, West Haven, CT 06516, USA.
3
Nanobiology Institute, Yale University, West Haven, CT 06516, USA; Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA; Institut des Sciences Biologiques, Centre National de la Recherche Scientifique (CNRS), Délégation Paris Michel-Ange, 3 rue Michel-Ange, 75794 Paris Cedex 16, France.
4
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. Electronic address: thomas.pollard@yale.edu.

Abstract

Cytokinesis in fission yeast cells depends on conventional myosin-II (Myo2) to assemble and constrict a contractile ring of actin filaments. Less is known about the functions of an unconventional myosin-II (Myp2) and a myosin-V (Myo51) that are also present in the contractile ring. Myo2 appears in cytokinetic nodes around the equator 10 min before spindle pole body separation (cell-cycle time, -10 min) independent of actin filaments, followed by Myo51 at time zero and Myp2 at time +20 min, both located between nodes and dependent on actin filaments. We investigated the contributions of these three myosins to cytokinesis using a severely disabled mutation of the essential myosin-II heavy-chain gene (myo2-E1) and deletion mutations of the other myosin heavy-chain genes. Cells with only Myo2 assemble contractile rings normally. Cells with either Myp2 or Myo51 alone can assemble nodes and actin filaments into contractile rings but complete assembly later than normal. Both Myp2 and Myo2 contribute to constriction of fully assembled rings at rates 55% that of normal in cells relying on Myp2 alone and 25% that of normal in cells with Myo2 alone. Myo51 alone cannot constrict rings but increases the constriction rate by Myo2 in Δmyp2 cells or Myp2 in myo2-E1 cells. Three myosins function in a hierarchal, complementary manner to accomplish cytokinesis, with Myo2 and Myo51 taking the lead during contractile ring assembly and Myp2 making the greatest contribution to constriction.

PMID:
26144970
PMCID:
PMC4526439
DOI:
10.1016/j.cub.2015.06.018
[Indexed for MEDLINE]
Free PMC Article
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