The Clp1/Cdc14 Phosphatase Contributes to the Robustness of Cytokinesis by Association with Anillin-Related Mid1

Cdc14 phosphatases antagonize cyclin-dependent kinase--directed phosphorylation events and are involved in several facets of cell cycle control. We investigate the role of the fission yeast Cdc14 homologue Clp1/Flp1 in cytokinesis. We find that Clp1/Flp1 is tethered at the contractile ring (CR) through its association with anillin-related Mid1. Fluorescent recovery after photo-bleaching analyses indicate that Mid1, unlike other tested CR components, is anchored at the cell midzone, and this physical property is likely to account for its scaf-folding role. By generating a mutation in mid1 that selectively disrupts Clp1/Flp1 tethering, we reveal the specific functional consequences of Clp1/Flp1 activity at the CR, including dephosphorylation of the essential CR component Cdc15, reductions in CR protein mobility, and CR resistance to mild perturbation. Our evidence indicates that Clp1/Flp1 must interact with the Mid1 scaffold to ensure the fidelity of Schizosaccharomyces pombe cytokinesis.