title: Conformational switching of the 26S proteasome enables substrate degradation.
abstract: The 26S proteasome is the major eukaryotic ATP-dependent protease, responsible for regulating the proteome through degradation of ubiquitin-tagged substrates. Its regulatory particle, containing the heterohexameric AAA+ ATPase motor and the essential deubiquitinase Rpn11, recognizes substrates, removes their ubiquitin chains and translocates them into the associated peptidase after unfolding, but detailed mechanisms remain unknown. Here we present the 26S proteasome structure from Saccharomyces cerevisiae during substrate degradation, showing that the regulatory particle switches from a preengaged to a translocation-competent conformation. This conformation is characterized by a rearranged ATPase ring with uniform subunit interfaces, a widened central channel coaxially aligned with the peptidase and a spiral orientation of pore loops that suggests a rapid progression of ATP-hydrolysis events around the ring. Notably, Rpn11 moves from an occluded position to directly above the central pore, thus facilitating substrate deubiquitination concomitant with translocation.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, California, USA.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Matyskiela
authors.forename: Gabriel C
authors.initials: GC
authors.lastname: Lander
authors.forename: Andreas
authors.initials: A
authors.lastname: Martin
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D020134:Catalytic Domain; D020285:Cryoelectron Microscopy; D010450:Endopeptidases / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D057149:Ubiquitinated Proteins / Q000378:metabolism
chemical_list: C115451:RPN11 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D057149:Ubiquitinated Proteins; D000255:Adenosine Triphosphate; D010450:Endopeptidases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease