title: Inherent asymmetry in the 26S proteasome is defined by the ubiquitin receptor RPN13.
abstract: The 26S double-capped proteasome is assembled in a hierarchic event that is orchestrated by dedicated set of chaperons. To date, all stoichiometric subunits are considered to be present in equal ratios, thus providing symmetry to the double-capped complex. Here, we show that although the vast majority (if not all) of the double-capped 26S proteasomes, both 19S complexes, contain the ubiquitin receptor Rpn10/S5a, only one of these 19S particles contains the additional ubiquitin receptor Rpn13, thereby defining asymmetry in the 26S proteasome. These results were validated in yeast and mammals, utilizing biochemical and unbiased AQUA-MS methodologies. Thus, the double-capped 26S proteasomes are asymmetric in their polyubiquitin binding capacity. Our data point to a potential new role for ubiquitin receptors as directionality factors that may participate in the prevention of simultaneous substrates translocation into the 20S from both 19S caps.
authors.affiliation: From the Department of Biochemistry, The Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Haifa 31096, Israel.
authors.forename: Dikla
authors.initials: D
authors.lastname: Berko
authors.forename: Ora
authors.initials: O
authors.lastname: Herkon
authors.forename: Ilana
authors.initials: I
authors.lastname: Braunstein
authors.forename: Elada
authors.initials: E
authors.lastname: Isakov
authors.forename: Yael
authors.initials: Y
authors.lastname: David
authors.forename: Tamar
authors.initials: T
authors.lastname: Ziv
authors.forename: Ami
authors.initials: A
authors.lastname: Navon
authors.forename: Ariel
authors.initials: A
authors.lastname: Stanhill
mesh_terms: D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D025821:Polyubiquitin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: C500781:ADRM1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C529711:RPN13 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025821:Polyubiquitin; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
keywords: Proteasome; Protein Complexes; Protein Degradation; Proteolytic Enzymes; S5a; Stoichiometry; Ubiquitin; Ubiquitin Receptor; rpn13