Mps1 Regulates Kinetochore-Microtubule Attachment Stability via the Ska Complex to Ensure Error-Free Chromosome Segregation.

Developmental cell 2017 Apr 24

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The spindle assembly checkpoint kinase Mps1 not only inhibits anaphase but also corrects erroneous attachments that could lead to missegregation and aneuploidy. However, Mps1's error correction-relevant substrates are unknown. Using a chemically tuned kinetochore-targeting assay, we show that Mps1 destabilizes microtubule attachments (K fibers) epistatically to Aurora B, the other major error-correcting kinase. Through quantitative proteomics, we identify multiple sites of Mps1-regulated phosphorylation at the outer kinetochore. Substrate modification was microtubule sensitive and opposed by PP2A-B56 phosphatases that stabilize chromosome-spindle attachment. Consistently, Mps1 inhibition rescued K-fiber stability after depleting PP2A-B56. We also identify the Ska complex as a key effector of Mps1 at the kinetochore-microtubule interface, as mutations that mimic constitutive phosphorylation destabilized K fibers in vivo and reduced the efficiency of the Ska complex's conversion from lattice diffusion to end-coupled microtubule binding in vitro. Our results reveal how Mps1 dynamically modifies kinetochores to correct improper attachments and ensure faithful chromosome segregation. Copyright © 2017 Elsevier Inc. All rights reserved.

Citation

John Maciejowski, Hauke Drechsler, Kathrin Grundner-Culemann, Edward R Ballister, Jose-Antonio Rodriguez-Rodriguez, Veronica Rodriguez-Bravo, Mathew J K Jones, Emily Foley, Michael A Lampson, Henrik Daub, Andrew D McAinsh, Prasad V Jallepalli. Mps1 Regulates Kinetochore-Microtubule Attachment Stability via the Ska Complex to Ensure Error-Free Chromosome Segregation. Developmental cell. 2017 Apr 24;41(2):143-156.e6