A mechanism for how Cdr1/Nim1 kinase promotes mitotic entry by inhibiting Wee1

Mol Biol Cell. 2019 Dec 1;30(25):3015-3023. doi: 10.1091/mbc.E19-08-0430. Epub 2019 Oct 23.

Abstract

To enter into mitosis, cells must shut off the cell cycle inhibitor Wee1. SAD family protein kinases regulate Wee1 signaling in yeast and humans. In Schizosaccharomyces pombe, two SAD kinases (Cdr1/Nim1 and Cdr2) act as upstream inhibitors of Wee1. Previous studies found that S. pombe Cdr1/Nim1 directly phosphorylates and inhibits Wee1 in vitro, but different results were obtained for budding yeast and human SAD kinases. Without a full understanding of Cdr1 action on Wee1, it has been difficult to assess the in vivo relevance and conservation of this mechanism. Here, we show that both Cdr1 and Cdr2 promote Wee1 phosphorylation in cells, but only Cdr1 inhibits Wee1 kinase activity. Inhibition occurs when Cdr1 phosphorylates a cluster of serine residues linking α-helices G and H of the Wee1 kinase domain. This region is highly divergent among different Wee1 proteins, consistent with distinct regulatory mechanisms. A wee(4A) mutant that impairs phosphorylation by Cdr1 delays mitotic entry and causes elongated cells. By disrupting and retargeting Cdr1 localization, we show that Cdr1 inhibition of Wee1 occurs in cells at cortical nodes formed by Cdr2. On the basis of our results, we propose a two-step model for inhibition of Wee1 by Cdr1 and Cdr2 at nodes.

Publication types

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

MeSH terms

  • CDC2 Protein Kinase / metabolism
  • Cell Cycle
  • Cell Cycle Proteins / metabolism*
  • Mitosis / physiology
  • Nuclear Proteins / metabolism
  • Phosphorylation
  • Protein Kinases / metabolism
  • Protein Transport
  • Protein-Serine-Threonine Kinases / metabolism*
  • Protein-Tyrosine Kinases / metabolism*
  • Schizosaccharomyces / metabolism
  • Schizosaccharomyces pombe Proteins / metabolism*

Substances

  • Cell Cycle Proteins
  • Nuclear Proteins
  • Schizosaccharomyces pombe Proteins
  • Protein Kinases
  • cdr1 protein, S pombe
  • wee1 protein, S pombe
  • Protein-Tyrosine Kinases
  • Cdr2 protein, S pombe
  • Protein-Serine-Threonine Kinases
  • CDC2 Protein Kinase