The CUE Domain of Cue1 Aligns Growing Ubiquitin Chains with Ubc7 for Rapid Elongation.
Ubiquitin conjugation is an essential process modulating protein function in eukaryotic cells. Surprisingly, little is known about how the progressive assembly of ubiquitin chains is managed by the responsible enzymes. Only recently has ubiquitin binding activity emerged as an important factor in chain formation. The Ubc7 activator Cue1 carries a ubiquitin binding CUE domain that substantially stimulates K48-linked polyubiquitination mediated by Ubc7. Our results from NMR-based analysis and in vitro ubiquitination reactions point out that two parameters accelerate ubiquitin chain assembly: the increasing number of CUE binding sites and the position of CUE binding within a growing chain. In particular, interactions with a ubiquitin moiety adjacent to the acceptor ubiquitin facilitate chain elongation. These data indicate a mechanism for ubiquitin binding in which Cue1 positions Ubc7 and the distal acceptor ubiquitin for rapid polyubiquitination. Disrupting this mechanism results in dysfunction of the ERAD pathway by a delayed turnover of substrates.
Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Strasse 10, 13125 Berlin-Buch, Germany.
Maximilian
M
von Delbrück
Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Strasse 9, 60439 Frankfurt am Main, Germany.
Andreas
A
Kniss
Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Strasse 9, 60439 Frankfurt am Main, Germany.
Vladimir V
VV
Rogov
Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Strasse 10, 13125 Berlin-Buch, Germany.
Lukas
L
Pluska
Ludwig Institute for Cancer Research, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, UK.
Katrin
K
Bagola
Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Strasse 9, 60439 Frankfurt am Main, Germany.
Frank
F
Löhr
Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Strasse 9, 60439 Frankfurt am Main, Germany.
Peter
P
Güntert
Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Strasse 10, 13125 Berlin-Buch, Germany; Institute for Biology, Humboldt Universität zu Berlin, Invalidenstrasse 43, 10115 Berlin, Germany. Electronic address: tsommer@mdc-berlin.de.
Thomas
T
Sommer
Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Strasse 9, 60439 Frankfurt am Main, Germany. Electronic address: vdoetsch@em.uni-frankfurt.de.
Volker
V
Dötsch
D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D060746:Endoplasmic Reticulum-Associated Degradation; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D025821:Polyubiquitin / Q000378:metabolism*; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D054730:Protein Interaction Domains and Motifs; D059748:Proteolysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
C109280:CUE1 protein, S cerevisiae; D002352:Carrier Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D025821:Polyubiquitin; C082461:UBC6 protein, S cerevisiae; C077072:UBC7 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes