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 PESTmotif 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.


Biological Sciences


Missouri Research Board
Missouri University of Science and Technology. Department of Biological Sciences


This work was supported by a Missouri Research Board grant to K.B.S.and K.E.S. were supported by the Department of Biological Sciences at Missouri S&T.

Keywords and Phrases

Budding Yeast; Contractile Actin Ring; Cytokinesis; Myosin; Septation

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Article - Journal

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© 2013 International Federation for Cell Biology, All rights reserved.

Publication Date

01 Apr 2013

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