Characterization of the roles of Blt1p in fission yeast cytokinesis.
Spatial and temporal regulation of cytokinesis is essential for cell division, yet the mechanisms that control the formation and constriction of the contractile ring are incompletely understood. In the fission yeast Schizosaccharomyces pombe proteins that contribute to the cytokinetic contractile ring accumulate during interphase in nodes-precursor structures around the equatorial cortex. During mitosis, additional proteins join these nodes, which condense to form the contractile ring. The cytokinesis protein Blt1p is unique in being present continuously in nodes from early interphase through to the contractile ring until cell separation. Blt1p was shown to stabilize interphase nodes, but its functions later in mitosis were unclear. We use analytical ultracentrifugation to show that purified Blt1p is a tetramer. We find that Blt1p interacts physically with Sid2p and Mob1p, a protein kinase complex of the septation initiation network, and confirm known interactions with F-BAR protein Cdc15p. Contractile rings assemble normally in blt1∆ cells, but the initiation of ring constriction and completion of cell division are delayed. We find three defects that likely contribute to this delay. Without Blt1p, contractile rings recruited and retained less Sid2p/Mob1p and Clp1p phosphatase, and β-glucan synthase Bgs1p accumulated slowly at the cleavage site.
Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103Department of Biological Sciences, Wellesley College, Wellesley, MA 02481-8203.
John W
JW
Goss
Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103.
Sunhee
S
Kim
Department of Biological Sciences, Wellesley College, Wellesley, MA 02481-8203.
Hannah
H
Bledsoe
Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103Department of Cell Biology, Yale University, New Haven, CT 06520-8103 thomas.pollard@yale.edu.
Thomas D
TD
Pollard
D018797:Cell Cycle Proteins / Q000737:chemistry / Q000502:physiology*; D048749:Cytokinesis; D007399:Interphase; D011494:Protein Kinases / Q000378:metabolism; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000502:physiology* / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D059008:Time-Lapse Imaging
C000595353:Blt1 protein, S pombe; D018797:Cell Cycle Proteins; C489694:Mid1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; C113816:Sid2 protein, S pombe