FIP200 Claw Domain Binding to p62 Promotes Autophagosome Formation at Ubiquitin Condensates

Mol Cell. 2019 Apr 18;74(2):330-346.e11. doi: 10.1016/j.molcel.2019.01.035. Epub 2019 Mar 7.

Abstract

The autophagy cargo receptor p62 facilitates the condensation of misfolded, ubiquitin-positive proteins and their degradation by autophagy, but the molecular mechanism of p62 signaling to the core autophagy machinery is unclear. Here, we show that disordered residues 326-380 of p62 directly interact with the C-terminal region (CTR) of FIP200. Crystal structure determination shows that the FIP200 CTR contains a dimeric globular domain that we designated the "Claw" for its shape. The interaction of p62 with FIP200 is mediated by a positively charged pocket in the Claw, enhanced by p62 phosphorylation, mutually exclusive with the binding of p62 to LC3B, and it promotes degradation of ubiquitinated cargo by autophagy. Furthermore, the recruitment of the FIP200 CTR slows the phase separation of ubiquitinated proteins by p62 in a reconstituted system. Our data provide the molecular basis for a crosstalk between cargo condensation and autophagosome formation.

Keywords: ATG8; X-ray crystallography; biochemistry; cell biology; phase separation; quality control; selective autophagy; ubiquitin.

Publication types

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

MeSH terms

  • Autophagosomes / chemistry
  • Autophagosomes / metabolism*
  • Autophagy / genetics
  • Autophagy-Related Proteins
  • Crystallography, X-Ray
  • Humans
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / genetics
  • Protein Conformation*
  • Protein Interaction Maps / genetics
  • Protein-Tyrosine Kinases / chemistry*
  • Protein-Tyrosine Kinases / genetics
  • Proteolysis
  • Sequestosome-1 Protein / chemistry*
  • Sequestosome-1 Protein / genetics
  • Signal Transduction / genetics
  • Ubiquitin / chemistry
  • Ubiquitin / genetics

Substances

  • Autophagy-Related Proteins
  • MAP1LC3B protein, human
  • Microtubule-Associated Proteins
  • RB1CC1 protein, human
  • SQSTM1 protein, human
  • Sequestosome-1 Protein
  • Ubiquitin
  • Protein-Tyrosine Kinases