Endoplasmic Reticulum Exit of Golgi-resident Defective for SREBP Cleavage (Dsc) E3 Ligase Complex Requires Its Activity

Raychaudhuri, Sumana; Espenshade, Peter J.

doi:10.1074/jbc.m114.630863

Cited by 9 publications

(13 citation statements)

References 39 publications

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“…Thus, the Dsc E3 ligase is required for proteasome‐dependent degradation of SREBP in rbd2∆ cells, demonstrating that the Dsc E3 ligase acts prior to Rbd2 in the biochemical pathway to cleave SREBP. To test specifically whether Sre2 precursor degradation requires Dsc E3 ligase activity, we studied a previously characterized, catalytically dead mutant of Dsc1 with a mutation in the Dsc1 RING domain ( dsc1‐C634A ) (Raychaudhuri & Espenshade, ). As observed for the dsc1 deletion, mutation of the Dsc1 RING domain restored Sre2 precursor in rbd2∆ cells (Fig E), showing that the Sre2 precursor degradation requires Dsc RING E3 ligase activity.…”

Section: Resultsmentioning

confidence: 99%

“…Together, these data suggest that SREBPs are substrates for the Dsc E3 ubiquitin ligase. However, recently we found that inhibition of Dsc E3 ligase activity prevents ER‐to‐Golgi transport of the Dsc complex, confounding the interpretation of these dsc mutant phenotypes (Raychaudhuri & Espenshade, ). Here, we observed that in rbd2∆ cells, SREBPs are degraded by the proteasome in a Dsc‐dependent manner (Figs and EV1).…”

Section: Discussionmentioning

confidence: 99%

“…Finally, is yeast SREBP ubiquitinylation required for cleavage? Our recent studies demonstrate that Dsc E3 ligase activity is required for Golgi localization of the Dsc E3 ligase complex (Raychaudhuri & Espenshade, 2015). Thus, mislocalization of the Dsc E3 ligase confounds the interpretation of dsc mutant data.…”

Section: Introductionmentioning

confidence: 99%

“…Cdc48 binds to the Dsc E3 ligase through the UBX domain of the Dsc5 subunit (Stewart et al, 2012). The Dsc E3 ligase complex possesses E3 ubiquitin ligase activity, and its complex architecture resembles the ER-associated degradation (ERAD) E3 ligase gp78 (Lloyd et al, 2013;Raychaudhuri & Espenshade, 2015). In ERAD, a membrane-associated E3 ligase core complex recognizes substrate proteins in the ER and mediates ubiquitinylation (Olzmann et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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A Golgi rhomboid protease Rbd2 recruits Cdc48 to cleave yeast SREBP

et al. 2016

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Hypoxic growth of fungi requires sterol regulatory element-binding protein (SREBP) transcription factors, and human opportunistic fungal pathogens require SREBP activation for virulence. Proteolytic release of fission yeast SREBPs from the membrane in response to low oxygen requires the Golgi membrane-anchored Dsc E3 ligase complex. Using genetic interaction arrays, we identified Rbd2 as a rhomboid family protease required for SREBP proteolytic processing. Rbd2 is an active, Golgi-localized protease that cleaves the transmembrane segment of the TatA rhomboid model substrate. Epistasis analysis revealed that the Dsc E3 ligase acts on SREBP prior to cleavage by Rbd2. Using APEX2 proximity biotinylation, we demonstrated that Rbd2 binds the AAA-ATPase Cdc48 through a C-terminal SHP box. Interestingly, SREBP cleavage required Rbd2 binding of Cdc48, consistent with Cdc48 acting to recruit ubiquitinylated substrates. In support of this claim, overexpressing a Cdc48-binding mutant of Rbd2 bypassed the Cdc48 requirement for SREBP cleavage, demonstrating that Cdc48 likely plays a role in SREBP recognition. In the absence of functional Rbd2, SREBP precursor is degraded by the proteasome, indicating that Rbd2 activity controls the balance between SREBP activation and degradation.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Golgi rhomboid protease Rbd2 recruits Cdc48 to cleave yeast SREBP

et al. 2016

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“…Dsc1 is a homolog of Saccharomyces cerevisiae Tul1, which is a Golgi ubiquitin E3 ligase, and Dsc2 is similar to the Der1 family proteins, which are critical for ER‐associated degradation (ERAD). Overall, the Golgi Dsc E3 ligase complex mimics the ERAD‐associated Hrd1 E3 ligase system (Stewart et al ., ; Stewart et al ., ; Raychaudhuri and Espenshade, ). Notably, there are no homologs of SCAP and S1P/S2P in Aspergillus .…”

Section: Introductionmentioning

confidence: 99%

The signal peptide peptidase SppA is involved in sterol regulatory element‐binding protein cleavage and hypoxia adaptation in Aspergillus nidulans

Bat-Ochir

Kwak

Koh

et al. 2016

Molecular Microbiology

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Using forward genetics, we revealed that the signal peptide peptidase (SPP) SppA, an aspartyl protease involved in regulated intramembrane proteolysis (RIP), is essential for hypoxia adaptation in Aspergillus nidulans, as well as hypoxia-sensitive mutant alleles of a sterol regulatory element-binding protein (SREBP) srbA and the Dsc ubiquitin E3 ligase complex dscA-E. Both null and dead activity [D337A] mutants of sppA failed to grow in hypoxia, and the growth defect of ΔsppA was complemented by nuclear SrbA-N381 expression. Additionally, SppA interacted with SrbA in the endoplasmic reticulum, where SppA localized in normoxia and hypoxia. Expression of the truncated SrbA-N414 covering the SrbA sequence prior to the second transmembrane region rescued the growth of ΔdscA but not of ΔsppA in hypoxia. Unlike ΔdscA and ΔdscA;ΔsppA double mutants, in which SrbA cleavage was blocked, the molecular weight of cleaved SrbA increased in ΔsppA compared to the control strain in immunoblot analyses. Overall, our data demonstrate the sequential cleavage of SrbA by Dsc-linked proteolysis followed by SppA, proposing a new model of RIP for SREBP cleavage in fungal hypoxia adaptation. Furthermore, the function of SppA in hypoxia adaptation was consistent in Aspergillus fumigatus, suggesting the potential roles of SppA in fungal pathogenesis.

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Identification of Rbd2 as a candidate protease for sterol regulatory element binding protein (SREBP) cleavage in fission yeast

Kim

et al. 2015

Biochemical and Biophysical Research Communications

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Endoplasmic Reticulum Exit of Golgi-resident Defective for SREBP Cleavage (Dsc) E3 Ligase Complex Requires Its Activity

Cited by 9 publications

References 39 publications

A Golgi rhomboid protease Rbd2 recruits Cdc48 to cleave yeast SREBP

A Golgi rhomboid protease Rbd2 recruits Cdc48 to cleave yeast SREBP

The signal peptide peptidase SppA is involved in sterol regulatory element‐binding protein cleavage and hypoxia adaptation in Aspergillus nidulans

Identification of Rbd2 as a candidate protease for sterol regulatory element binding protein (SREBP) cleavage in fission yeast

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