TY - JOUR
T1 - Degradation signals for ubiquitin-proteasome dependent cytosolic protein quality control (CytoQC) in yeast
AU - Maurer, Matthew J.
AU - Spear, Eric D.
AU - Yu, Allen T.
AU - Lee, Evan J.
AU - Shahzad, Saba
AU - Michaelis, Susan
N1 - Funding Information:
We thank Rich Gardner, Randy Hampton, Karen Arndt, Davis Ng, Ray Deshaies, and Avrom Caplan for strains and plasmids. This work was supported by a grant (R01 GM051508) from the National Institutes of Health (NIH) to S.M., and a Johns Hopkins Institute for Basic Biomedical Science Bridge grant. Figure 7 Ltn1-mediated degradation of the Ura3-HA
Publisher Copyright:
© 2016 Maurer et al.
PY - 2016/7/1
Y1 - 2016/7/1
N2 - Cellular protein quality control (PQC) systems selectively target misfolded or otherwise aberrant proteins for degradation by the ubiquitin-proteasome system (UPS). How cells discern abnormal from normal proteins remains incompletely understood, but involves in part the recognition between ubiquitin E3 ligases and degradation signals (degrons) that are exposed in misfolded proteins. PQC is compartmentalized in the cell, and a great deal has been learned in recent years about ER-associated degradation (ERAD) and nuclear quality control. In contrast, a comprehensive view of cytosolic quality control (CytoQC) has yet to emerge, and will benefit from the development of a well-defined set of model substrates. In this study, we generated an isogenic "degron library" in Saccharomyces cerevisiae consisting of short sequences appended to the C-terminus of a reporter protein, Ura3. About half of these degron-containing proteins are substrates of the integral membrane E3 ligase Doa10, which also plays a pivotal role in ERAD and some nuclear protein degradation. Notably, some of our degron fusion proteins exhibit dependence on the E3 ligase Ltn1/Rkr1 for degradation, apparently by a mechanism distinct from its known role in ribosomal quality control of translationally paused proteins. Ubr1 and San1, E3 ligases involved in the recognition of some misfolded CytoQC substrates, are largely dispensable for the degradation of our degron-containing proteins. Interestingly, the Hsp70/Hsp40 chaperone/cochaperones Ssa1,2 and Ydj1, are required for the degradation of all constructs tested. Taken together, the comprehensive degron library presented here provides an important resource of isogenic substrates for testing candidate PQC components and identifying new ones.
AB - Cellular protein quality control (PQC) systems selectively target misfolded or otherwise aberrant proteins for degradation by the ubiquitin-proteasome system (UPS). How cells discern abnormal from normal proteins remains incompletely understood, but involves in part the recognition between ubiquitin E3 ligases and degradation signals (degrons) that are exposed in misfolded proteins. PQC is compartmentalized in the cell, and a great deal has been learned in recent years about ER-associated degradation (ERAD) and nuclear quality control. In contrast, a comprehensive view of cytosolic quality control (CytoQC) has yet to emerge, and will benefit from the development of a well-defined set of model substrates. In this study, we generated an isogenic "degron library" in Saccharomyces cerevisiae consisting of short sequences appended to the C-terminus of a reporter protein, Ura3. About half of these degron-containing proteins are substrates of the integral membrane E3 ligase Doa10, which also plays a pivotal role in ERAD and some nuclear protein degradation. Notably, some of our degron fusion proteins exhibit dependence on the E3 ligase Ltn1/Rkr1 for degradation, apparently by a mechanism distinct from its known role in ribosomal quality control of translationally paused proteins. Ubr1 and San1, E3 ligases involved in the recognition of some misfolded CytoQC substrates, are largely dispensable for the degradation of our degron-containing proteins. Interestingly, the Hsp70/Hsp40 chaperone/cochaperones Ssa1,2 and Ydj1, are required for the degradation of all constructs tested. Taken together, the comprehensive degron library presented here provides an important resource of isogenic substrates for testing candidate PQC components and identifying new ones.
KW - E3 ligase Doa10
KW - Ltn1
KW - Protein quality control
KW - Proteostasis
KW - Ubiquitin proteasome system
UR - http://www.scopus.com/inward/record.url?scp=84978413857&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84978413857&partnerID=8YFLogxK
U2 - 10.1534/g3.116.027953
DO - 10.1534/g3.116.027953
M3 - Article
C2 - 27172186
AN - SCOPUS:84978413857
SN - 2160-1836
VL - 6
SP - 1853
EP - 1866
JO - G3: Genes, Genomes, Genetics
JF - G3: Genes, Genomes, Genetics
IS - 7
ER -