Structural basis of Atg8 activation by a homodimeric E1, Atg7

Mol Cell. 2011 Nov 4;44(3):462-75. doi: 10.1016/j.molcel.2011.08.035.

Abstract

E1 enzymes activate ubiquitin-like proteins and transfer them to cognate E2 enzymes. Atg7, a noncanonical E1, activates two ubiquitin-like proteins, Atg8 and Atg12, and plays a crucial role in autophagy. Here, we report crystal structures of full-length Atg7 and its C-terminal domain bound to Atg8 and MgATP, as well as a solution structure of Atg8 bound to the extreme C-terminal domain (ECTD) of Atg7. The unique N-terminal domain (NTD) of Atg7 is responsible for Atg3 (E2) binding, whereas its C-terminal domain is comprised of a homodimeric adenylation domain (AD) and ECTD. The structural and biochemical data demonstrate that Atg8 is initially recognized by the C-terminal tail of ECTD and is then transferred to an AD, where the Atg8 C terminus is attacked by the catalytic cysteine to form a thioester bond. Atg8 is then transferred via a trans mechanism to the Atg3 bound to the NTD of the opposite protomer within a dimer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Autophagy-Related Protein 7
  • Autophagy-Related Protein 8 Family
  • Autophagy-Related Proteins
  • Binding Sites
  • Crystallography, X-Ray
  • Enzyme Activation
  • Microtubule-Associated Proteins / chemistry*
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Models, Molecular
  • Multienzyme Complexes
  • Mutation
  • Protein Conformation
  • Protein Interaction Domains and Motifs
  • Protein Interaction Mapping
  • Protein Multimerization
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Structure-Activity Relationship
  • Time Factors
  • Ubiquitin-Conjugating Enzymes / chemistry
  • Ubiquitin-Conjugating Enzymes / metabolism

Substances

  • ATG7 protein, S cerevisiae
  • ATG8 protein, S cerevisiae
  • Autophagy-Related Protein 8 Family
  • Autophagy-Related Proteins
  • Microtubule-Associated Proteins
  • Multienzyme Complexes
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphate
  • Ubiquitin-Conjugating Enzymes
  • Autophagy-Related Protein 7
  • ATG3 protein, S cerevisiae

Associated data

  • PDB/2LI5
  • PDB/3VH1
  • PDB/3VH2
  • PDB/3VH3
  • PDB/3VH4