Mechanism of gate opening in the 20S proteasome by the proteasomal ATPases.

摘要: Substrates enter the cylindrical 20S proteasome through a gated channel that is regulated by ATPases in 19S regulatory particle eukaryotes or homologous PAN ATPase complex archaea. These contain conserved C-terminal hydrophobic-tyrosine-X (HbYX) motif triggers gate opening upon ATP binding. Using cryo-electron microscopy, we identified sites archaeal where PAN's residues bind and determined structures of its closed open forms. Peptides containing HbYX to pockets between neighboring alpha subunits they interact with required for opening. This interaction induces rotation displacement reverse-turn loop stabilizes open-gate conformation. mechanism differs from PA26/28, which lacks does not cause subunit rotation. findings demonstrated how ATPases' C termini function facilitate substrate entry.