Abstract
The quality control of intracellular proteins is achieved by degrading misfolded proteins which cannot be refolded by molecular chaperones. In eukaryotes, such degradation is handled primarily by the ubiquitin-proteasome system. However, it remains unclear whether and how protein quality control deploys various deubiquitinases. To address this question, we screened deletions or mutation of the 20 deubiquitinase genes in Saccharomyces cerevisiae and discovered that almost half of the mutations slowed the removal of misfolded proteins whereas none of the remaining mutations accelerated this process significantly. Further characterization revealed that Ubp6 maintains the level of free ubiquitin to promote the elimination of misfolded cytosolic proteins, while Ubp3 supports the degradation of misfolded cytosolic and ER luminal proteins by different mechanisms.
- Abbreviations
- chr
- chromosome
- CPY
- carboxypeptidase Y
- CytoQC
- cytosolic (protein) quality control
- dis
- disomic
- DTT
- dithiothreitol
- DUb
- deubiquitinase
- ER
- endoplasmic reticulum
- ERQC
- ER (protein) quality control
- GFP
- green fluorescent protein
- HA
- hemagglutinin tag
- IP
- immunoprecipitation
- PAGE
- polyacrylamide gel electrophoresis
- PBS
- phosphate-buffered saline
- PIC
- protease inhibitor cocktail
- PMSF
- phenylmethylsulfonyl fluoride
- PrA
- proteinase A
- pUB
- pRS313 centromeric plasmid expressing ubiquitin from TDH3 promoter
- pUBK63R
- pRS424 2μ plasmid expressing ubiquitin from PRC1 promoter
- QC
- (protein) quality control
- qPCR
- quantitative PCR
- SDS
- sodium dodecyl sulfate
- ss
- signal sequence
- TCA
- trichloroacetic acid
- Ub
- ubiquitin
- UPS
- ubiquitin-proteasome system
- WT
- wild-type