A polybasic domain in aPKC mediates Par6-dependent control of membrane targeting and kinase activity

J Cell Biol. 2020 Jul 6;219(7):e201903031. doi: 10.1083/jcb.201903031.

Abstract

Mechanisms coupling the atypical PKC (aPKC) kinase activity to its subcellular localization are essential for cell polarization. Unlike other members of the PKC family, aPKC has no well-defined plasma membrane (PM) or calcium binding domains, leading to the assumption that its subcellular localization relies exclusively on protein-protein interactions. Here we show that in both Drosophila and mammalian cells, the pseudosubstrate region (PSr) of aPKC acts as a polybasic domain capable of targeting aPKC to the PM via electrostatic binding to PM PI4P and PI(4,5)P2. However, physical interaction between aPKC and Par-6 is required for the PM-targeting of aPKC, likely by allosterically exposing the PSr to bind PM. Binding of Par-6 also inhibits aPKC kinase activity, and such inhibition can be relieved through Par-6 interaction with apical polarity protein Crumbs. Our data suggest a potential mechanism in which allosteric regulation of polybasic PSr by Par-6 couples the control of both aPKC subcellular localization and spatial activation of its kinase activity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Allosteric Regulation
  • Animals
  • Animals, Genetically Modified
  • Cell Membrane / enzymology*
  • Cell Membrane / ultrastructure
  • Cell Polarity / genetics
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / enzymology*
  • Drosophila melanogaster / genetics
  • Embryo, Nonmammalian
  • Epithelial Cells / enzymology
  • Epithelial Cells / ultrastructure
  • Gene Expression Regulation
  • Genes, Reporter
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Larva / cytology
  • Larva / enzymology
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Phosphatidylinositol 4,5-Diphosphate / chemistry
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Phosphatidylinositol Phosphates / chemistry
  • Phosphatidylinositol Phosphates / metabolism
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Kinase C / chemistry
  • Protein Kinase C / genetics
  • Protein Kinase C / metabolism*
  • Signal Transduction
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Cyan Fluorescent Protein
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Membrane Proteins
  • PARD6A protein, human
  • PBRM1 protein, human
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositol Phosphates
  • Transcription Factors
  • crb protein, Drosophila
  • phosphatidylinositol 4-phosphate
  • Green Fluorescent Proteins
  • protein kinase C zeta
  • Par-6 protein, Drosophila
  • Protein Kinase C
  • aPKC protein, Drosophila