Structural basis for autophagy inhibition by the human Rubicon-Rab7 complex

Proc Natl Acad Sci U S A. 2020 Jul 21;117(29):17003-17010. doi: 10.1073/pnas.2008030117. Epub 2020 Jul 6.

Abstract

Rubicon is a potent negative regulator of autophagy and a potential target for autophagy-inducing therapeutics. Rubicon-mediated inhibition of autophagy requires the interaction of the C-terminal Rubicon homology (RH) domain of Rubicon with Rab7-GTP. Here we report the 2.8-Å crystal structure of the Rubicon RH domain in complex with Rab7-GTP. Our structure reveals a fold for the RH domain built around four zinc clusters. The switch regions of Rab7 insert into pockets on the surface of the RH domain in a mode that is distinct from those of other Rab-effector complexes. Rubicon residues at the dimer interface are required for Rubicon and Rab7 to colocalize in living cells. Mutation of Rubicon RH residues in the Rab7-binding site restores efficient autophagic flux in the presence of overexpressed Rubicon, validating the Rubicon RH domain as a promising therapeutic target.

Keywords: Rab GTPase; autophagy; crystal structure.

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

  • Autophagy / physiology*
  • Autophagy-Related Proteins* / chemistry
  • Autophagy-Related Proteins* / metabolism
  • Autophagy-Related Proteins* / physiology
  • Crystallography, X-Ray
  • HeLa Cells
  • Humans
  • Models, Molecular
  • Protein Binding
  • Protein Domains / physiology
  • rab GTP-Binding Proteins* / chemistry
  • rab GTP-Binding Proteins* / metabolism
  • rab GTP-Binding Proteins* / physiology
  • rab7 GTP-Binding Proteins

Substances

  • Autophagy-Related Proteins
  • RUBCN protein, human
  • rab7 GTP-Binding Proteins
  • rab7 GTP-binding proteins, human
  • rab GTP-Binding Proteins