title: Cdk1-dependent phosphorylation of Iqg1 governs actomyosin ring assembly prior to cytokinesis.
abstract: Contraction of the actomyosin ring (AMR) provides the centripetal force that drives cytokinesis. In budding yeast (Saccharomyces cerevisiae), assembly and contraction of the AMR is coordinated with membrane deposition and septum formation at the bud neck. A central player in this process is Iqg1, which promotes recruitment of actin to the myosin ring and links AMR assembly with that of septum-forming components. We observed early actin recruitment in response to inhibition of cyclin-dependent kinase 1 (Cdk1) activity, and we find that the Cdk1-dependent phosphorylation state of Iqg1 is a determining factor in the timing of bud neck localization of both Iqg1 and actin, with both proteins accumulating prematurely in cells expressing nonphosphorylatable Iqg1 mutants. We also identified the primary septum regulator Hof1 as a binding partner of Iqg1, providing a regulatory link between the septation and contractile pathways that cooperate to complete cytokinesis.
authors.affiliation: Departments of Physiology and Biochemistry & Biophysics, University of California, San Francisco, CA 94158, USA.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Naylor
authors.forename: David O
authors.initials: DO
authors.lastname: Morgan
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000705:Anaphase; D017489:CDC28 Protein Kinase, S cerevisiae / Q000502:physiology*; D048749:Cytokinesis; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D010766:Phosphorylation; D055503:Protein Multimerization; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D020703:ras GTPase-Activating Proteins / Q000378:metabolism*
chemical_list: C116847:HOF1 protein, S cerevisiae; C101203:IQ motif containing GTPase activating protein 1; C113979:MLC1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D018994:Myosin Light Chains; D029701:Saccharomyces cerevisiae Proteins; D020703:ras GTPase-Activating Proteins; D000205:Actomyosin; D017489:CDC28 Protein Kinase, S cerevisiae
keywords: Actomyosin ring; Cdk1; Cytokinesis; Iqg1