4J2G: Atg13 Horma Domain

Autophagy-related 13 (Atg13) is a key early-acting factor in autophagy and the major locus for nutrient-dependent regulation of autophagy by Tor. The 2.3-A resolution crystal structure of the N-terminal domain of Atg13 reveals a previously unidentified HORMA (Hop1p, Rev1p and Mad2) domain similar to that of the spindle checkpoint protein Mad2. Mad2 has two different stable conformations, O-Mad2 and C-Mad2, and the Atg13 HORMA structure corresponds to the C-Mad2 state. The Atg13 HORMA domain is required for autophagy and for recruitment of the phosphatidylinositol (PI) 3-kinase subunit Atg14 but is not required for Atg1 interaction or Atg13 recruitment to the preautophagosomal structure. The Atg13 HORMA structure reveals a pair of conserved Arg residues that constitute a putative phosphate sensor. One of the Arg residues is in the region corresponding to the "safety belt" conformational switch of Mad2, suggesting conformational regulation of phosphate binding. These two Arg residues are essential for autophagy, suggesting that the Atg13 HORMA domain could function as a phosphoregulated conformational switch.
PDB ID: 4J2GDownload
MMDB ID: 108509
PDB Deposition Date: 2013/2/4
Updated in MMDB: 2013/04
Experimental Method:
x-ray diffraction
Resolution: 2.29  Å
Source Organism:
Similar Structures:
Biological Unit for 4J2G: monomeric; determined by author
Molecular Components in 4J2G
Label Count Molecule
Protein (1 molecule)
Molecule annotation
Chemical (1 molecule)
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