Importin binding mediates the intramolecular regulation of anillin during cytokinesis

Mol Biol Cell. 2020 May 15;31(11):1124-1139. doi: 10.1091/mbc.E20-01-0006. Epub 2020 Apr 2.

Abstract

Cytokinesis occurs by the ingression of an actomyosin ring that cleaves a cell into two daughters. This process is tightly controlled to avoid aneuploidy, and we previously showed that active Ran coordinates ring positioning with chromatin. Active Ran is high around chromatin, and forms an inverse gradient to cargo-bound importins. We found that the ring component anillin contains a nuclear localization signal (NLS) that binds to importin and is required for its function during cytokinesis. Here we reveal the mechanism whereby importin binding favors a conformation required for anillin's recruitment to the equatorial cortex. Active RhoA binds to the RhoA-binding domain causing an increase in accessibility of the nearby C2 domain containing the NLS. Importin binding subsequently stabilizes a conformation that favors interactions for cortical recruitment. In addition to revealing a novel mechanism for the importin-mediated regulation of a cortical protein, we also show how importin binding positively regulates protein function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Contractile Proteins / metabolism*
  • Contractile Proteins / physiology
  • Cytokinesis / physiology*
  • HeLa Cells
  • Humans
  • Karyopherins / metabolism*
  • Karyopherins / physiology
  • Microtubules / metabolism
  • Nuclear Localization Signals
  • Protein Binding
  • Spindle Apparatus / metabolism
  • ran GTP-Binding Protein / metabolism
  • rhoA GTP-Binding Protein / metabolism

Substances

  • Contractile Proteins
  • Karyopherins
  • Nuclear Localization Signals
  • anillin
  • ran GTP-Binding Protein
  • rhoA GTP-Binding Protein