Monoubiquitination of RPN10 regulates substrate recruitment to the proteasome.
The proteasome recognizes its substrates via a diverse set of ubiquitin receptors, including subunits Rpn10/S5a and Rpn13. In addition, shuttling factors, such as Rad23, recruit substrates to the proteasome by delivering ubiquitinated proteins. Despite the increasing understanding of the factors involved in this process, the regulation of substrate delivery remains largely unexplored. Here we report that Rpn10 is monoubiquitinated in vivo and that this modification has profound effects on proteasome function. Monoubiquitination regulates the capacity of Rpn10 to interact with substrates by inhibiting Rpn10's ubiquitin-interacting motif (UIM). We show that Rsp5, a member of NEDD4 ubiquitin-protein ligase family, and Ubp2, a deubiquitinating enzyme, control the levels of Rpn10 monoubiquitination in vivo. Notably, monoubiquitination of Rpn10 is decreased under stress conditions, suggesting a mechanism of control of receptor availability mediated by the Rsp5-Ubp2 system. Our results reveal an unanticipated link between monoubiquitination signal and regulation of proteasome function.
Isasa
Marta
M
Institut de Biologia Molecular de Barcelona, CSIC, Barcelona Scientific Park, Baldiri i Reixac 15-21, 08028 Barcelona, Spain.
Katz
Elijah J
EJ
Kim
Woong
W
Yugo
Verónica
V
González
Sheyla
S
Kirkpatrick
Donald S
DS
Thomson
Timothy M
TM
Finley
Daniel
D
Gygi
Steven P
SP
Crosas
Bernat
B
D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D000075702:Nedd4 Ubiquitin Protein Ligases; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
D056827:Endosomal Sorting Complexes Required for Transport; C122019:RPN10 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D043743:Ubiquitin-Protein Ligase Complexes; D000075702:Nedd4 Ubiquitin Protein Ligases; D044767:Ubiquitin-Protein Ligases; D010450:Endopeptidases; D046988:Proteasome Endopeptidase Complex; C059237:ubiquitin-Nalpha-protein hydrolase; C469287:RSP5 protein, S cerevisiae; D008239:Lysine