3C92: Thermoplasma Acidophilum 20s Proteasome With A Closed Gate

Substrates enter the cylindrical 20S proteasome through a gated channel that is regulated by the ATPases in the 19S regulatory particle in eukaryotes or the homologous PAN ATPase complex in archaea. These ATPases contain a conserved C-terminal hydrophobic-tyrosine-X (HbYX) motif that triggers gate opening upon ATP binding. Using cryo-electron microscopy, we identified the sites in the archaeal 20S where PAN's C-terminal residues bind and determined the structures of the gate in its closed and open forms. Peptides containing the HbYX motif bind to 20S in the pockets between neighboring alpha subunits where they interact with conserved residues required for gate opening. This interaction induces a rotation in the alpha subunits and displacement of a reverse-turn loop that stabilizes the open-gate conformation. This mechanism differs from that of PA26/28, which lacks the HbYX motif and does not cause alpha subunit rotation. These findings demonstrated how the ATPases' C termini function to facilitate substrate entry.
PDB ID: 3C92Download
MMDB ID: 65871
PDB Deposition Date: 2008/2/14
Updated in MMDB: 2008/09
Experimental Method:
electron microscopy
Resolution: 6.8  Å
Source Organism:
Similar Structures:
Biological Unit for 3C92: 28-meric; determined by author
Molecular Components in 3C92
Label Count Molecule
Proteins (28 molecules)
Proteasome Subunit Alpha(Gene symbol: TA_RS06650)
Molecule annotation
Proteasome Subunit Beta(Gene symbol: TA_RS03155)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB