Mutation of Hof1 PEST motif phosphorylation sites leads to retention of Hof1 at the bud neck and a decrease in the rate of myosin contraction.
Regulation of actomyosin ring contraction is important for the coordination of cytokinesis with mitosis. Hof1, a member of the Pombe Cdc15 homology (PCH) family of proteins, is required for efficient cytokinesis in budding yeast. Phosphorylation of Hof1 depends on the mitotic exit network (MEN), and its degradation at the end of mitosis depends on its PEST motif and interaction with the E3 ligase Grr1. To test the hypothesis that targeted destruction of Hof1 temporally couples mitotic exit with contraction of the actomyosin ring, we mutated the Hof1 PEST motif to prevent phosphorylation and subsequent degradation. These mutations increased the amount of Hof1 at the bud neck during cytokinesis, resulted in smaller bud neck diameter, and slowed the rate of myosin contraction. However, Hof1 PEST motif phosphorylation site mutants did not have cytokinesis defects, indicating that regulation of Hof1 levels does not control the onset of actomyosin ring contraction as predicted.
Department of Biological Sciences, Missouri University of Science and Technology, 105 Schrenk Hall, 400 W. 11th St., Rolla, Missouri, 65401, USA. shannonk@mst.edu.
Katherine E
KE
Stockstill
Jungeun
J
Park
Rachel
R
Wille
Grace
G
Bay
Avery
A
Joseph
Katie B
KB
Shannon
D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D048749:Cytokinesis; D044783:F-Box Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009218:Myosins / Q000502:physiology; D010766:Phosphorylation; D054730:Protein Interaction Domains and Motifs; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D044783:F-Box Proteins; C116847:HOF1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C071032:GRR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D009218:Myosins
budding yeast; contractile actin ring; cytokinesis; myosin; septation