Intrinsic conformational transitions contribute to the catalytic action of many enzymes. Here we use a single-molecule approach to demonstrate how such transitions are linked to the catalytic sites of the eukaryotic proteasome, an essential protease of the ubiquitin pathway. The active sites of the cylindrical proteasomal core particle are located in a central chamber accessible through gated entry channels. By using atomic force microscopy, we found continual alternation between open and closed gate conformations. We analyzed the relative abundance of these conformers in wild-type and mutated yeast core particles upon exposure to substrates or inhibitors. Our data indicate that the dynamic gate can be opened by allosteric coupling to a tetrahedral transition state at any of the working active centers. The results point to the N(alpha)-amine of the N-terminal active site threonyl residue as the major effector group responsible for triggering the essential conformational switch.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|