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Peptide-based Identification of Functional Motifs and their Binding Partners
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Peptide-based Identification of Functional Motifs and their Binding Partners

Published on: June 30, 2013

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Aurora B opposes PP1 function in mitosis by phosphorylating the conserved PP1-binding RVxF motif in PP1 regulatory

Isha Nasa1, Scott F Rusin2, Arminja N Kettenbach3,4

  • 1Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.

Science Signaling
|May 17, 2018
PubMed

Insights

Mitotic protein kinase Aurora B phosphorylates a specific motif in Protein Phosphatase 1 (PP1) regulatory proteins, disrupting PP1 holoenzyme assembly. This phosphorylation controls mitotic progression by regulating PP1 activity during cell division.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Protein Phosphatase 1 (PP1) is crucial for eukaryotic dephosphorylation, opposing serine/threonine kinases.
  • PP1 achieves substrate specificity via over 200 regulatory proteins, often binding through the RVxF motif.
  • Mitosis requires precise regulation of protein phosphorylation and dephosphorylation.

Purpose of the Study:

  • To investigate the role of phosphorylation within PP1 regulatory proteins during mitosis.
  • To identify the kinase responsible for phosphorylating specific PP1-binding motifs.
  • To elucidate how this phosphorylation impacts PP1 holoenzyme assembly and function.

Main Methods:

  • Phosphorylation analysis of RVxF motifs during mitosis.
  • Identification of the kinase governing RVxF motif phosphorylation using biochemical assays.
  • Generation and application of a phospho-specific antibody (anti-RVp[S/T]F).
  • Proteomic analysis to identify PP1 binding partners regulated by this mechanism.

Main Results:

  • A subset of RVxF motifs (RV[S/T]F) are phosphorylated during mitosis, abrogating PP1 binding.
  • Aurora B kinase is the primary kinase responsible for phosphorylating these mitotic RVxF motifs.
  • High stoichiometry of RVp[S/T]F phosphorylation disrupts PP1 holoenzyme assembly, maintaining substrate phosphorylation during mitosis.
  • The phospho-specific antibody identified known (KNL1, CDCA2, RIF1) and novel (UBR5, ASPM, SEH1, ELYS) PP1 regulatory proteins.

Conclusions:

  • Phosphorylation of RV[S/T]F motifs by Aurora B is a key regulatory mechanism during mitosis.
  • This mechanism fine-tunes PP1 activity by controlling holoenzyme assembly.
  • Coordinated regulation of Aurora B and PP1 is essential for accurate mitotic progression.

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