scholarly journals An N-end rule pathway that recognizes proline and destroys gluconeogenic enzymes

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. eaal3655 ◽  
Author(s):  
Shun-Jia Chen ◽  
Xia Wu ◽  
Brandon Wadas ◽  
Jang-Hyun Oh ◽  
Alexander Varshavsky
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ubiquitin Ligase ◽  
Sequence Motifs ◽  
Proteolytic System ◽  
Gluconeogenic Enzymes ◽  
Gluconeogenic Enzyme ◽  
Adjacent Sequence

Cells synthesize glucose if deprived of it, and destroy gluconeogenic enzymes upon return to glucose-replete conditions. We found that the Gid4 subunit of the ubiquitin ligase GID in the yeast Saccharomyces cerevisiae targeted the gluconeogenic enzymes Fbp1, Icl1, and Mdh2 for degradation. Gid4 recognized the N-terminal proline (Pro) residue and the ~5-residue-long adjacent sequence motifs. Pck1, the fourth gluconeogenic enzyme, contains Pro at position 2; Gid4 directly or indirectly recognized Pro at position 2 of Pck1, contributing to its targeting. These and related results identified Gid4 as the recognition component of the GID-based proteolytic system termed the Pro/N-end rule pathway. Substrates of this pathway include gluconeogenic enzymes that bear either the N-terminal Pro residue or a Pro at position 2, together with adjacent sequence motifs.

scholarly journals Aminopeptidases trim Xaa-Pro proteins, initiating their degradation by the Pro/N-degron pathway

2021 ◽  
Vol 118 (43) ◽  
pp. e2115430118
Author(s):  
Shun-Jia Chen ◽  
Leehyeon Kim ◽  
Hyun Kyu Song ◽  
Alexander Varshavsky
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Enzymatic Activity ◽  
Amino Acid Residue ◽  
Ubiquitin Ligase ◽  
Proteolytic System ◽  
A Subunit

N-degron pathways are proteolytic systems that recognize proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Our previous work identified Gid4 as a recognition component (N-recognin) of the Saccharomyces cerevisiae proteolytic system termed the proline (Pro)/N-degron pathway. Gid4 is a subunit of the oligomeric glucose-induced degradation (GID) ubiquitin ligase. Gid4 targets proteins through the binding to their Nt-Pro residue. Gid4 is also required for degradation of Nt-Xaa-Pro (Xaa is any amino acid residue) proteins such as Nt-[Ala-Pro]-Aro10 and Nt-[Ser-Pro]-Pck1, with Pro at position 2. Here, we show that specific aminopeptidases function as components of the Pro/N-degron pathway by removing Nt-Ala or Nt-Ser and yielding Nt-Pro, which can be recognized by Gid4-GID. Nt-Ala is removed by the previously uncharacterized aminopeptidase Fra1. The enzymatic activity of Fra1 is shown to be essential for the GID-dependent degradation of Nt-[Ala-Pro]-Aro10. Fra1 can also trim Nt-[Ala-Pro-Pro-Pro] (stopping immediately before the last Pro) and thereby can target for degradation a protein bearing this Nt sequence. Nt-Ser is removed largely by the mitochondrial/cytosolic/nuclear aminopeptidase Icp55. These advances are relevant to eukaryotes from fungi to animals and plants, as Fra1, Icp55, and the GID ubiquitin ligase are conserved in evolution. In addition to discovering the mechanism of targeting of Xaa-Pro proteins, these insights have also expanded the diversity of substrates of the Pro/N-degron pathway.

scholarly journals Gid10 as an alternative N-recognin of the Pro/N-degron pathway

2019 ◽  
Vol 116 (32) ◽  
pp. 15914-15923 ◽  
Author(s):  
Artem Melnykov ◽  
Shun-Jia Chen ◽  
Alexander Varshavsky
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Ubiquitin Ligase ◽  
Growth Conditions ◽  
26S Proteasome ◽  
Sequence Motifs ◽  
Yeast Protein ◽  
Substrate Specificities ◽  
Nonfermentable Carbon Source ◽  
A Subunit

In eukaryotes, N-degron pathways (formerly “N-end rule pathways”) comprise a set of proteolytic systems whose unifying feature is their ability to recognize proteins containing N-terminal degradation signals called N-degrons, thereby causing degradation of these proteins by the 26S proteasome or autophagy. Gid4, a subunit of the GID ubiquitin ligase in the yeast Saccharomyces cerevisiae, is the recognition component (N-recognin) of the GID-mediated Pro/N-degron pathway. Gid4 targets proteins by recognizing their N-terminal Pro residues or a Pro at position 2, in the presence of distinct adjoining sequence motifs. Under conditions of low or absent glucose, cells make it through gluconeogenesis. When S. cerevisiae grows on a nonfermentable carbon source, its gluconeogenic enzymes Fbp1, Icl1, Mdh2, and Pck1 are expressed and long-lived. Transition to a medium containing glucose inhibits the synthesis of these enzymes and induces their degradation by the Gid4-dependent Pro/N-degron pathway. While studying yeast Gid4, we identified a similar but uncharacterized yeast protein (YGR066C), which we named Gid10. A screen for N-terminal peptide sequences that can bind to Gid10 showed that substrate specificities of Gid10 and Gid4 overlap but are not identical. Gid10 is not expressed under usual (unstressful) growth conditions, but is induced upon starvation or osmotic stresses. Using protein binding analyses and degradation assays with substrates of GID, we show that Gid10 can function as a specific N-recognin of the Pro/N-degron pathway.

scholarly journals Recognition of nonproline N-terminal residues by the Pro/N-degron pathway

2020 ◽  
Vol 117 (25) ◽  
pp. 14158-14167 ◽  
Author(s):  
Cheng Dong ◽  
Shun-Jia Chen ◽  
Artem Melnykov ◽  
Sara Weirich ◽  
Kelly Sun ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Crystal Structures ◽  
Ubiquitin Ligase ◽  
Substrate Recognition ◽  
26S Proteasome ◽  
Yeast Cells ◽  
Sequence Motifs ◽  
Wild Type ◽  
Rapid Degradation ◽  
A Subunit

Eukaryotic N-degron pathways are proteolytic systems whose unifying feature is their ability to recognize proteins containing N-terminal (Nt) degradation signals called N-degrons, and to target these proteins for degradation by the 26S proteasome or autophagy. GID4, a subunit of the GID ubiquitin ligase, is the main recognition component of the proline (Pro)/N-degron pathway. GID4 targets proteins through their Nt-Pro residue or a Pro at position 2, in the presence of specific downstream sequence motifs. Here we show that human GID4 can also recognize hydrophobic Nt-residues other than Pro. One example is the sequence Nt-IGLW, bearing Nt-Ile. Nt-IGLW binds to wild-type human GID4 with aKdof 16 μM, whereas the otherwise identical Nt-Pro–bearing sequence PGLW binds to GID4 more tightly, with aKdof 1.9 μM. Despite this difference in affinities of GID4 for Nt-IGLW vs. Nt-PGLW, we found that the GID4-mediated Pro/N-degron pathway of the yeastSaccharomyces cerevisiaecan target an Nt-IGLW–bearing protein for rapid degradation. We solved crystal structures of human GID4 bound to a peptide bearing Nt-Ile or Nt-Val. We also altered specific residues of human GID4 and measured the affinities of resulting mutant GID4s for Nt-IGLW and Nt-PGLW, thereby determining relative contributions of specific GID4 residues to the GID4-mediated recognition of Nt-Pro vs. Nt-residues other than Pro. These and related results advance the understanding of targeting by the Pro/N-degron pathway and greatly expand the substrate recognition range of the GID ubiquitin ligase in both human and yeast cells.

scholarly journals The Zn-finger of Saccharomyces cerevisiae Rad18 and its adjacent region mediate interaction with Rad5

2021 ◽  
Author(s):  
Orsolya Frittmann ◽  
Vamsi K Gali ◽  
Miklos Halmai ◽  
Robert Toth ◽  
Zsuzsanna Gyorfy ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Ubiquitin Ligase ◽  
Dna Lesions ◽  
Template Switching ◽  
Adjacent Region ◽  
Yeast Two Hybrid ◽  
Replication Complex ◽  
Two Hybrid

Abstract DNA damages that hinder the movement of the replication complex can ultimately lead to cell death. To avoid that, cells possess several DNA damage bypass mechanisms. The Rad18 ubiquitin ligase controls error-free and mutagenic pathways that help the replication complex to bypass DNA lesions by monoubiquitylating PCNA at stalled replication forks. In Saccharomyces cerevisiae, two of the Rad18 governed pathways are activated by monoubiquitylated PCNA and they involve translesion synthesis polymerases, whereas a third pathway needs subsequent polyubiquitylation of the same PCNA residue by another ubiquitin ligase the Rad5 protein, and it employs template switching. The goal of this study was to dissect the regulatory role of the multidomain Rad18 in DNA damage bypass using a structure-function based approach. Investigating deletion and point mutant RAD18 variants in yeast genetic and yeast two-hybrid assays we show that the Zn-finger of Rad18 mediates its interaction with Rad5, and the N-terminal adjacent region is also necessary for Rad5 binding. Moreover, results of the yeast two-hybrid and in vivo ubiquitylation experiments raise the possibility that direct interaction between Rad18 and Rad5 might not be necessary for the function of the Rad5 dependent pathway. The presented data also reveal that yeast Rad18 uses different domains to mediate its association with itself and with Rad5. Our results contribute to better understanding of the complex machinery of DNA damage bypass pathways.

scholarly journals CAT8, a new zinc cluster-encoding gene necessary for derepression of gluconeogenic enzymes in the yeast Saccharomyces cerevisiae.

1995 ◽  
Vol 15 (4) ◽  
pp. 1915-1922 ◽  
Author(s):  
D Hedges ◽  
M Proft ◽  
K D Entian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Carbon Source ◽  
Gene Activation ◽  
Carbon Sources ◽  
Source Analysis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Gluconeogenic Enzymes ◽  
Zinc Cluster ◽  
Promoter Fusion

The expression of gluconeogenic fructose-1,6-bisphosphatase (encoded by the FBP1 gene) depends on the carbon source. Analysis of the FBP1 promoter revealed two upstream activating elements, UAS1FBP1 and UAS2FBP1, which confer carbon source-dependent regulation on a heterologous reporter gene. On glucose media neither element was activated, whereas after transfer to ethanol a 100-fold derepression was observed. This gene activation depended on the previously identified derepression genes CAT1 (SNF1) (encoding a protein kinase) and CAT3 (SNF4) (probably encoding a subunit of Cat1p [Snf1p]). Screening for mutations specifically involved in UAS1FBP1 derepression revealed the new recessive derepression mutation cat8. The cat8 mutants also failed to derepress UAS2FBP1, and these mutants were unable to grow on nonfermentable carbon sources. The CAT8 gene encodes a zinc cluster protein related to Saccharomyces cerevisiae Gal4p. Deletion of CAT8 caused a defect in glucose derepression which affected all key gluconeogenic enzymes. Derepression of glucose-repressible invertase and maltase was still normally regulated. A CAT8-lacZ promoter fusion revealed that the CAT8 gene itself is repressed by Cat4p (Mig1p). These results suggest that gluconeogenic genes are derepressed upon binding of Cat8p, whose synthesis depends on the release of Cat4p (Mig1p) from the CAT8 promoter. However, gluconeogenic promoters are still glucose repressed in cat4 mutants, which indicates that in addition to its transcription, the Cat8p protein needs further activation. The observation that multicopy expression of CAT8 reverses the inability of cat1 and cat3 mutants to grow on ethanol indicates that Cat8p might be the substrate of the Cat1p/Cat3p protein kinase.

scholarly journals Glucose derepression of gluconeogenic enzymes in Saccharomyces cerevisiae correlates with phosphorylation of the gene activator Cat8p.

1997 ◽  
Vol 17 (5) ◽  
pp. 2502-2510 ◽  
Author(s):  
F Randez-Gil ◽  
N Bojunga ◽  
M Proft ◽  
K D Entian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Transcriptional Activation ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glucose Repression ◽  
Sodium Dodecyl ◽  
Binding Motif ◽  
Gluconeogenic Enzymes ◽  
Zinc Cluster ◽  
Activating Function

The Cat8p zinc cluster protein is essential for growth of Saccharomyces cerevisiae with nonfermentable carbon sources. Expression of the CAT8 gene is subject to glucose repression mainly caused by Mig1p. Unexpectedly, the deletion of the Mig1p-binding motif within the CAT8 promoter did not increase CAT8 transcription; moreover, it resulted in a loss of CAT8 promoter activation. Insertion experiments with a promoter test plasmid confirmed that this regulatory 20-bp element influences glucose repression and derepression as well. This finding suggests an upstream activating function of this promoter region, which is Mig1p independent, as delta mig1 mutants are still able to derepress the CAT8 promoter. No other putative binding sites such as a Hap2/3/4/5p site and an Abf1p consensus site were functional with respect to glucose-regulated CAT8 expression. Fusions of Cat8p with the Gal4p DNA-binding domain mediated transcriptional activation. This activation capacity was still carbon source regulated and depended on the Cat1p (Snf1p) protein kinase, which indicated that Cat8p needs posttranslational modification to reveal its gene-activating function. Indeed, Western blot analysis on sodium dodecyl sulfate-gels revealed a single band (Cat8pI) with crude extracts from glucose-grown cells, whereas three bands (Cat8pI, -II, and -III) were identified in derepressed cells. Derepression-specific Cat8pII and -III resulted from differential phosphorylation, as shown by phosphatase treatment. Only the most extensively phosphorylated modification (Cat8pIII) depended on the Cat1p (Snf1p) kinase, indicating that another protein kinase is responsible for modification form Cat8pII. The occurrence of Cat8pIII was strongly correlated with the derepression of gluconeogenic enzymes (phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase) and gluconeogenic PCK1 mRNA. Furthermore, glucose triggered the dephosphorylation of Cat8pIII, but this did not depend on the Glc7p (Cid1p) phosphatase previously described as being involved in invertase repression. These results confirm our current model that glucose derepression of gluconeogenic genes needs Cat8p phosphorylation and additionally show that a still unknown transcriptional activator is also involved.

scholarly journals Overlapping function of Hrd1 and Ste24 in translocon quality control provides robust channel surveillance

2020 ◽  
Vol 295 (47) ◽  
pp. 16113-16120
Author(s):  
Avery M. Runnebohm ◽  
Kyle A. Richards ◽  
Courtney Broshar Irelan ◽  
Samantha M. Turk ◽  
Halie E. Vitali ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Biological Membranes ◽  
The Other ◽  
Growth Defect ◽  
Zinc Metalloprotease

Translocation of proteins across biological membranes is essential for life. Proteins that clog the endoplasmic reticulum (ER) translocon prevent the movement of other proteins into the ER. Eukaryotes have multiple translocon quality control (TQC) mechanisms to detect and destroy proteins that persistently engage the translocon. TQC mechanisms have been defined using a limited panel of substrates that aberrantly occupy the channel. The extent of substrate overlap among TQC pathways is unknown. In this study, we found that two TQC enzymes, the ER-associated degradation ubiquitin ligase Hrd1 and zinc metalloprotease Ste24, promote degradation of characterized translocon-associated substrates of the other enzyme in Saccharomyces cerevisiae. Although both enzymes contribute to substrate turnover, our results suggest a prominent role for Hrd1 in TQC. Yeast lacking both Hrd1 and Ste24 exhibit a profound growth defect, consistent with overlapping function. Remarkably, two mutations that mildly perturb post-translational translocation and reduce the extent of aberrant translocon engagement by a model substrate diminish cellular dependence on TQC enzymes. Our data reveal previously unappreciated mechanistic complexity in TQC substrate detection and suggest that a robust translocon surveillance infrastructure maintains functional and efficient translocation machinery.

scholarly journals NPR1 Kinase and RSP5-BUL1/2 Ubiquitin Ligase Control GLN3-dependent Transcription in Saccharomyces cerevisiae

2004 ◽  
Vol 279 (36) ◽  
pp. 37512-37517 ◽  
Author(s):  
José L. Crespo ◽  
Stephen B. Helliwell ◽  
Christa Wiederkehr ◽  
Philippe Demougin ◽  
Brian Fowler ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ubiquitin Ligase

scholarly journals Vid24p, a Novel Protein Localized to the Fructose-1,6-bisphosphatase–containing Vesicles, Regulates Targeting of Fructose-1,6-bisphosphatase from the Vesicles to the Vacuole for Degradation

1998 ◽  
Vol 140 (6) ◽  
pp. 1347-1356 ◽  
Author(s):  
Meng-Chieh Chiang ◽  
Hui-Ling Chiang
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Membrane Protein ◽  
Critical Role ◽  
Carbon Sources ◽  
Degradation Pathway ◽  
Yeast Cells ◽  
Fructose 1,6 Bisphosphatase ◽  
Peripheral Membrane Protein ◽  
Gluconeogenic Enzyme ◽  
Novel Protein

Glucose regulates the degradation of the key gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase), in Saccharomyces cerevisiae. FBPase is targeted from the cytosol to a novel type of vesicle, and then to the vacuole for degradation when yeast cells are transferred from medium containing poor carbon sources to fresh glucose. To identify proteins involved in the FBPase degradation pathway, we cloned our first VID (vacuolar import and degradation) gene. The VID24 gene was identified by complementation of the FBPase degradation defect of the vid24-1 mutant. Vid24p is a novel protein of 41 kD and is synthesized in response to glucose. Vid24p is localized to the FBPase-containing vesicles as a peripheral membrane protein. In the absence of functional Vid24p, FBPase accumulates in the vesicles and fails to move to the vacuole, suggesting that Vid24p regulates FBPase targeting from the vesicles to the vacuole. FBPase sequestration into the vesicles is not affected in the vid24-1 mutant, indicating that Vid24p acts after FBPase sequestration into the vesicles has occurred. Vid24p is the first protein identified that marks the FBPase-containing vesicles and plays a critical role in delivering FBPase from the vesicles to the vacuole for degradation.

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