Aim44p regulates phosphorylation of Hof1p to promote contractile ring closure during cytokinesis in budding yeast.
Whereas actomyosin and septin ring organization and function in cytokinesis are thoroughly described, little is known regarding the mechanisms by which the actomyosin ring interacts with septins and associated proteins to coordinate cell division. Here we show that the protein product of YPL158C, Aim44p, undergoes septin-dependent recruitment to the site of cell division. Aim44p colocalizes with Myo1p, the type II myosin of the contractile ring, throughout most of the cell cycle. The Aim44p ring does not contract when the actomyosin ring closes. Instead, it forms a double ring that associates with septin rings on mother and daughter cells after cell separation. Deletion of AIM44 results in defects in contractile ring closure. Aim44p coimmunoprecipitates with Hof1p, a conserved F-BAR protein that binds both septins and type II myosins and promotes contractile ring closure. Deletion of AIM44 results in a delay in Hof1p phosphorylation and altered Hof1p localization. Finally, overexpression of Dbf2p, a kinase that phosphorylates Hof1p and is required for relocalization of Hof1p from septin rings to the contractile ring and for Hof1p-triggered contractile ring closure, rescues the cytokinesis defect observed in aim44 cells. Our studies reveal a novel role for Aim44p in regulating contractile ring closure through effects on Hof1p.
Department of Pathology and Cell Biology, Columbia University, New York, NY 10027 School of Engineering and Science, Jacobs University Bremen, 28759 Bremen, Germany.
Dana M Alessi
DM
Wolken
Joseph
J
McInnes
Liza A
LA
Pon
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D048749:Cytokinesis / Q000235:genetics*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D058112:Septins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
C000592814:Aim44 protein, S cerevisiae; D018797:Cell Cycle Proteins; C116847:HOF1 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; C112936:MYO1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C085768:DBF2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D058112:Septins; D018995:Myosin Heavy Chains