title: Proteasome recruitment and activation of the Uch37 deubiquitinating enzyme by Adrm1.
abstract: Uch37 is one of the three principal deubiquitinating enzymes (DUBs), and the only ubiquitin carboxy-terminal hydrolase (UCH)-family protease, that is associated with mammalian proteasomes. We show that Uch37 is responsible for the ubiquitin isopeptidase activity in the PA700 (19S) proteasome regulatory complex. PA700 isopeptidase disassembles Lys 48-linked polyubiquitin specifically from the distal end of the chain, a property that may be used to clear poorly ubiquitinated or unproductively bound substrates from the proteasome. To better understand Uch37 function and the mechanism responsible for its specificity, we investigated how Uch37 is recruited to proteasomes. Uch37 binds through Adrm1, a previously unrecognized orthologue of Saccharomyces cerevisiae Rpn13p, which in turn is bound to the S1 (also known as Rpn2) subunit of the 19S complex. Adrm1 (human Rpn13, hRpn13) binds the carboxy-terminal tail of Uch37, a region that is distinct from the UCH catalytic domain, which we show inhibits Uch37 activity. Following binding, Adrm1 relieves Uch37 autoinhibition, accelerating the hydrolysis of ubiquitin-7-amido-4-methylcoumarin (ubiquitin-AMC). However, neither Uch37 alone nor the Uch37-Adrm1 or Uch37-Adrm1-S1 complexes can hydrolyse di-ubiquitin efficiently; rather, incorporation into the 19S complex is required to enable processing of polyubiquitin chains.
authors.affiliation: Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
authors.forename: Tingting
authors.initials: T
authors.lastname: Yao
authors.forename: Ling
authors.initials: L
authors.lastname: Song
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: George N
authors.initials: GN
authors.lastname: DeMartino
authors.forename: Laurence
authors.initials: L
authors.lastname: Florens
authors.forename: Selene K
authors.initials: SK
authors.lastname: Swanson
authors.forename: Michael P
authors.initials: MP
authors.lastname: Washburn
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Conaway
authors.forename: Joan Weliky
authors.initials: JW
authors.lastname: Conaway
authors.forename: Robert E
authors.initials: RE
authors.lastname: Cohen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D004789:Enzyme Activation; D006801:Humans; D006868:Hydrolysis; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D025801:Ubiquitin / Q000378:metabolism*; D043222:Ubiquitin Thiolesterase
chemical_list: C500781:ADRM1 protein, human; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D002268:Carboxypeptidases; C421245:UCHL5 protein, human; D043222:Ubiquitin Thiolesterase; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease