Nov 26, 2019

Kinetochore phosphatases suppress autonomous kinase activity to control the spindle assembly checkpoint

BioRxiv : the Preprint Server for Biology
Marilia Henriques CordeiroAdrian T Saurin

Abstract

Local phosphatase regulation is critical for determining when phosphorylation signals are activated or deactivated. A typical example is the spindle assembly checkpoint (SAC) during mitosis, which regulates kinetochore PP1 and PP2A-B56 activities to switch-off signalling events at the correct time. In this case, kinetochore phosphatase activation dephosphorylates MELT motifs on KNL1 to remove SAC proteins, including the BUB complex. We show here that, surprisingly, neither PP1 or PP2A are required to dephosphorylate the MELT motifs. Instead, they remove polo-like kinase 1 (PLK1) from the BUB complex, which can otherwise maintain MELT phosphorylation in an autocatalytic manner. This is their principle role in the SAC, because both phosphatases become redundant if PLK1 is inhibited or BUB-PLK1 interaction is prevented. Therefore, phosphatase regulation is critical for the SAC, but primarily to restrain and extinguish autonomous kinase activity. We propose that these circuits have evolved to generate a semi-autonomous SAC signal that can be synchronously silenced following kinetochore-microtubule tension.

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Mentioned in this Paper

Phosphoric Monoester Hydrolases
CASC5 protein, human
BUB-3 protein, C elegans
PP1 Antibody
Kinetochore Microtubule
Phosphatase Regulator Activity
Protein Phosphatase 2A
ACP Protocol
Protein Domain
KNTC1 protein, human

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