NPM1 exhibits structural and dynamic heterogeneity upon phase separation with the p14ARF tumor suppressor

J Magn Reson. 2020 Jan:310:106646. doi: 10.1016/j.jmr.2019.106646. Epub 2019 Nov 11.

Abstract

Nucleophosmin (NPM1) is an abundant nucleolar protein that aids in the maturation of pre-ribosomal particles and participates in oncogenic stress responses through its interaction with the Alternative Reading Frame tumor suppressor (p14ARF). NPM1 mediates multiple mechanisms of phase separation which contribute to the liquid-like properties of nucleoli. However, the effects of phase separation on the structure and dynamics of NPM1 are poorly understood. Here we show that NPM1 undergoes phase separation with p14ARF in vitro, forming condensates that immobilize both proteins. We probed the structure and dynamics of NPM1 within the condensed phase using solid-state NMR spectroscopy. Our results demonstrate that within the condensed phase, the NPM1 oligomerization domain forms an immobile scaffold, while the central intrinsically disordered region and the C-terminal nucleic acid binding domain exhibit relative mobility.

Keywords: Biomolecular condensates; MAS; NPM1; Phase separation; p14ARF; ssNMR.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Nucleolus / chemistry
  • Cloning, Molecular
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Nuclear Proteins / chemistry*
  • Nucleophosmin
  • Open Reading Frames
  • Protein Structure, Secondary
  • Tumor Suppressor Protein p14ARF / chemistry*

Substances

  • NPM1 protein, human
  • Nuclear Proteins
  • Tumor Suppressor Protein p14ARF
  • Nucleophosmin