Probing the interactions of meiotic spindle proteins revealed a new phospho-regulated interaction at microtubule plus ends

Abstract

The establishment of correct kinetochore-microtubule attachments is a critical aspect of cell division, and one that is particularly error-prone in oocytes. Mutations of the sentin gene in Drosophila have been previously shown to lead to meiosis-specific errors in kinetochore-microtubule attachments in oocytes, but the mechanism by which Sentin promotes error correction has not been previously investigated. In this study, I identified the interactors of 10 Drosophila meiotic spindle proteins by immunoprecipitation followed by mass spectrometry. This revealed a previously uncharacterised direct interaction between the microtubule plus end-binding protein Sentin and the microtubule depolymerase Klp10A. Sentin protein is phosphorylated in a Polo kinase-dependent manner in ovaries, and the Sentin-Klp10A interaction was perturbed upon Polo kinase knockdown. Sentin’s N-terminus contains several predicted and in vivo phosphorylated phosphosites, which predominantly fit a Polo kinase consensus motif. Direct phosphorylation of Sentin by Plk1 furthermore promoted its interaction with Klp10A in vitro. Overall, this research identified a new phosphorylation-regulated protein-protein interaction occurring during meiosis I.