title: A Single α Helix Drives Extensive Remodeling of the Proteasome Lid and Completion of Regulatory Particle Assembly.
abstract: Most short-lived eukaryotic proteins are degraded by the proteasome. A proteolytic core particle (CP) capped by regulatory particles (RPs) constitutes the 26S proteasome complex. RP biogenesis culminates with the joining of two large subcomplexes, the lid and base. In yeast and mammals, the lid appears to assemble completely before attaching to the base, but how this hierarchical assembly is enforced has remained unclear. Using biochemical reconstitutions, quantitative cross-linking/mass spectrometry, and electron microscopy, we resolve the mechanistic basis for the linkage between lid biogenesis and lid-base joining. Assimilation of the final lid subunit, Rpn12, triggers a large-scale conformational remodeling of the nascent lid that drives RP assembly, in part by relieving steric clash with the base. Surprisingly, this remodeling is triggered by a single Rpn12 α helix. Such assembly-coupled conformational switching is reminiscent of viral particle maturation and may represent a commonly used mechanism to enforce hierarchical assembly in multisubunit complexes.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA. Electronic address: robert.tomko@med.fsu.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Tomko
authors.affiliation: California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Taylor
authors.affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King's Buildings, Max Born Crescent, Mayfield Road, Edinburgh EH9 3BF, Scotland.
authors.forename: Zhuo A
authors.initials: ZA
authors.lastname: Chen
authors.affiliation: Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, PRC.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
authors.affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King's Buildings, Max Born Crescent, Mayfield Road, Edinburgh EH9 3BF, Scotland; Department of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany.
authors.forename: Juri
authors.initials: J
authors.lastname: Rappsilber
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA. Electronic address: mark.hochstrasser@yale.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Hochstrasser
mesh_terms: D004926:Escherichia coli / Q000378:metabolism; D013058:Mass Spectrometry; D008854:Microscopy, Electron; D008958:Models, Molecular; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: C074096:RPN12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease