scholarly journals Translational Regulation of Pmt1 and Pmt2 by Bfr1 Affects Unfolded Protein O-Mannosylation

2019 ◽  
Vol 20 (24) ◽  
pp. 6220 ◽  
Author(s):  
Joan Castells-Ballester ◽  
Natalie Rinis ◽  
Ilgin Kotan ◽  
Lihi Gal ◽  
Daniela Bausewein ◽  
...  
Keyword(s):  
Quality Control ◽  
Translational Regulation ◽  
Secretory Pathway ◽  
Rna Binding ◽  
Protein Quality ◽  
Fluorescent Protein ◽  
Brefeldin A ◽  
Protein Quality Control ◽  
Ribosome Profiling ◽  
Unfolded Protein

O-mannosylation is implicated in protein quality control in Saccharomyces cerevisiae due to the attachment of mannose to serine and threonine residues of un- or misfolded proteins in the endoplasmic reticulum (ER). This process also designated as unfolded protein O-mannosylation (UPOM) that ends futile folding cycles and saves cellular resources is mainly mediated by protein O-mannosyltransferases Pmt1 and Pmt2. Here we describe a genetic screen for factors that influence O-mannosylation in yeast, using slow-folding green fluorescent protein (GFP) as a reporter. Our screening identifies the RNA binding protein brefeldin A resistance factor 1 (Bfr1) that has not been linked to O-mannosylation and ER protein quality control before. We find that Bfr1 affects O-mannosylation through changes in Pmt1 and Pmt2 protein abundance but has no effect on PMT1 and PMT2 transcript levels, mRNA localization to the ER membrane or protein stability. Ribosome profiling reveals that Bfr1 is a crucial factor for Pmt1 and Pmt2 translation thereby affecting unfolded protein O-mannosylation. Our results uncover a new level of regulation of protein quality control in the secretory pathway.

scholarly journals Translational regulation of Pmt1 and Pmt2 by Bfr1 affects unfolded protein O-mannosylation

2019 ◽  
Author(s):  
Joan Castells-Ballester ◽  
Natalie Rinis ◽  
Ilgin Kotan ◽  
Lihi Gal ◽  
Daniela Bausewein ◽  
...  
Keyword(s):  
Quality Control ◽  
Translational Regulation ◽  
Secretory Pathway ◽  
Rna Binding ◽  
Protein Quality ◽  
Brefeldin A ◽  
Protein Quality Control ◽  
Ribosome Profiling ◽  
Protein Abundance ◽  
Unfolded Protein

ABSTRACTO-mannosylation is implicated in protein quality control in Saccharomyces cerevisiae due to the attachment of mannose to serine and threonine residues of un- or misfolded proteins in the endoplasmic reticulum (ER). This process also designated as unfolded protein O-mannosylation (UPOM) that ends futile folding cycles and saves cellular resources is mainly mediated by protein O-mannosyltransferases Pmt1 and Pmt2. Here we describe a genetic screen for factors that influence O-mannosylation in yeast, using slow-folding GFP as a reporter. Our screening identifies the RNA binding protein brefeldin A resistance factor 1 (Bfr1) that has not been linked to O-mannosylation and ER protein quality control before. We find that Bfr1 affects O-mannosylation through changes in Pmt1 and Pmt2 protein abundance, but has no effect on PMT1 and PMT2 transcript levels, mRNA localization to the ER membrane or protein stability. Ribosome profiling reveals that Bfr1 is a crucial factor for Pmt1 and Pmt2 translation thereby affecting unfolded protein O-mannosylation. Our results uncover a new level of regulation of protein quality control in the secretory pathway.

scholarly journals Protein quality control in the secretory pathway

2019 ◽  
Vol 218 (10) ◽  
pp. 3171-3187 ◽  
Author(s):  
Zhihao Sun ◽  
Jeffrey L. Brodsky
Keyword(s):  
Quality Control ◽  
Protein Folding ◽  
Secretory Pathway ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Misfolded Proteins ◽  
Unfolded Protein ◽  
Protein Biogenesis ◽  
The Unfolded Protein Response ◽  
Protein Response

Protein folding is inherently error prone, especially in the endoplasmic reticulum (ER). Even with an elaborate network of molecular chaperones and protein folding facilitators, misfolding can occur quite frequently. To maintain protein homeostasis, eukaryotes have evolved a series of protein quality-control checkpoints. When secretory pathway quality-control pathways fail, stress response pathways, such as the unfolded protein response (UPR), are induced. In addition, the ER, which is the initial hub of protein biogenesis in the secretory pathway, triages misfolded proteins by delivering substrates to the proteasome or to the lysosome/vacuole through ER-associated degradation (ERAD) or ER-phagy. Some misfolded proteins escape the ER and are instead selected for Golgi quality control. These substrates are targeted for degradation after retrieval to the ER or delivery to the lysosome/vacuole. Here, we discuss how these guardian pathways function, how their activities intersect upon induction of the UPR, and how decisions are made to dispose of misfolded proteins in the secretory pathway.

Protein quality control at the mitochondrion

2016 ◽  
Vol 60 (2) ◽  
pp. 213-225 ◽  
Author(s):  
Wolfgang Voos ◽  
Witold Jaworek ◽  
Anne Wilkening ◽  
Michael Bruderek
Keyword(s):  
Quality Control ◽  
Structural Integrity ◽  
Protein Quality ◽  
Mitochondrial Protein ◽  
Protein Quality Control ◽  
Eukaryotic Cell ◽  
Control Mechanisms ◽  
Biochemical Processes ◽  
Unfolded Protein ◽  
Protein Response

Mitochondria are essential constituents of a eukaryotic cell by supplying ATP and contributing to many mayor metabolic processes. As endosymbiotic organelles, they represent a cellular subcompartment exhibiting many autonomous functions, most importantly containing a complete endogenous machinery responsible for protein expression, folding and degradation. This article summarizes the biochemical processes and the enzymatic components that are responsible for maintaining mitochondrial protein homoeostasis. As mitochondria lack a large part of the required genetic information, most proteins are synthesized in the cytosol and imported into the organelle. After reaching their destination, polypeptides must fold and assemble into active proteins. Under pathological conditions, mitochondrial proteins become misfolded or damaged and need to be repaired with the help of molecular chaperones or eventually removed by specific proteases. Failure of these protein quality control mechanisms results in loss of mitochondrial function and structural integrity. Recently, novel mechanisms have been identified that support mitochondrial quality on the organellar level. A mitochondrial unfolded protein response allows the adaptation of chaperone and protease activities. Terminally damaged mitochondria may be removed by a variation of autophagy, termed mitophagy. An understanding of the role of protein quality control in mitochondria is highly relevant for many human pathologies, in particular neurodegenerative diseases.

scholarly journals Comparison of endogenously expressed fluorescent protein fusions behaviour for protein quality control and cellular aging research

2021 ◽  
Author(s):  
Kara L. Schneider ◽  
Adam Wollman ◽  
Thomas Nyström ◽  
Sviatlana Shashkova
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Stress Protein ◽  
Protein Quality Control ◽  
Cellular Aging ◽  
Aging Research ◽  
Ageing Research ◽  
Microbiology Research

AbstractThe yeast Hsp104 protein disaggregase is often used as a reporter for misfolded or damaged protein aggregates and protein quality control and ageing research. Observing endogenously expressed Hsp104 fusions with fluorescent proteins is a popular approach to follow post stress protein aggregation, inclusion formation and disaggregation. Overall, such protein fusions used in molecular and microbiology research are often sparsely characterised. To address this issue, we performed a comparative assessment of Hsp104 fluorescent fusions function and behaviour. We provide experimental evidence that molecular behaviour may not only be altered by introducing a fluorescent protein tag but also varies depending on the fluorophore within the fusion. Although our findings are especially applicable to protein quality control and ageing research in yeast, similar effects and points may play a role in other eukaryotic systems.

scholarly journals Modulating protein quality control

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Lars Plate ◽  
Ryan J Paxman ◽  
R Luke Wiseman ◽  
Jeffery W Kelly
Keyword(s):  
Quality Control ◽  
Small Molecules ◽  
Unfolded Protein Response ◽  
Protein Misfolding ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Misfolding Diseases ◽  
Protein Response

Small molecules that modulate the unfolded protein response have the potential to treat a variety of human protein misfolding diseases.

scholarly journals Mycobacterium tuberculosis Rv0991c is a redox-regulated molecular chaperone

2020 ◽  
Author(s):  
Samuel H. Becker ◽  
Kathrin Ulrich ◽  
Avantika Dhabaria ◽  
Beatrix Ueberheide ◽  
William Beavers ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Quality Control ◽  
Molecular Chaperone ◽  
Protein Quality ◽  
Bacterial Pathogen ◽  
Protein Quality Control ◽  
Effective Strategies ◽  
Unfolded Protein ◽  
Hsp70 Chaperone

ABSTRACTThe bacterial pathogen Mycobacterium (M.) tuberculosis is the leading cause of death by an infectious disease among humans. Here, we describe a previously uncharacterized M. tuberculosis protein, Rv0991c, as a molecular chaperone that is activated by oxidation. Rv0991c has homologues in most bacterial lineages and appears to function analogously to the well-characterized Escherichia coli redox-regulated chaperone Hsp33, despite a dissimilar protein sequence. Rv0991c is transcriptionally co-regulated with hsp60 and hsp70 chaperone genes in M. tuberculosis, suggesting that Rv0991c functions with these chaperones in maintaining protein quality control. Supporting this hypothesis, we found that, like oxidized Hsp33, oxidized Rv0991c prevents the aggregation of a model unfolded protein in vitro, and promotes its refolding by the M. tuberculosis Hsp70 chaperone system. Furthermore, Rv0991c interacts with DnaK and associates with many other M. tuberculosis proteins. Importantly, we found Rv0991c is required for the full virulence of M. tuberculosis in mice. We therefore propose that Rv0991c, which we named “Ruc” (redox-regulated protein with unstructured C-terminus), represents a founding member of a new chaperone family that protects M. tuberculosis and other species from proteotoxicity during oxidative stress.IMPORTANCEM. tuberculosis infections are responsible for more than one million human deaths per year. Developing effective strategies to combat this disease requires a greater understanding of M. tuberculosis biology. As in all cells, protein quality control is essential for the viability of M. tuberculosis, which likely faces proteome stress within a host. Here, we identify an M. tuberculosis protein, Ruc, that gains chaperone activity upon oxidation. Ruc represents a previously unrecognized family of redox-regulated chaperones found throughout the bacterial super-kingdom. In addition to elucidating the activity of this chaperone, we found that Ruc was required for full M. tuberculosis virulence in mice. This work contributes to a growing appreciation that oxidative stress may provide a particular strain on protein stability in cells, and may likewise play a role in M. tuberculosis pathogenesis.

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