Acidic proteins of the large ribosomal subunit in Saccharomyces cerevisiae. Effect of phosphorylation

Biochemistry ◽  
1984 ◽  
Vol 23 (2) ◽  
pp. 390-396 ◽  
Author(s):  
F. Juan Vidales ◽  
M. T. Saenz Robles ◽  
J. P. G. Ballesta
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Subunit ◽  
Large Ribosomal Subunit ◽  
Acidic Proteins

scholarly journals CAT tails drive on- and off-ribosome degradation of stalled polypeptides

2018 ◽  
Author(s):  
Cole S. Sitron ◽  
Onn Brandman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quality Control ◽  
Ubiquitin Ligase ◽  
Ribosomal Subunit ◽  
Protein Homeostasis ◽  
Large Ribosomal Subunit ◽  
Backup Route ◽  
Carboxy Terminal

SummaryStalled translation produces incomplete, ribosome-associated polypeptides that Ribosome-associated Quality Control (RQC) targets for degradation via the ubiquitin ligase Ltn1. During this process, the Rqc2 protein and large ribosomal subunit elongate stalled polypeptides with carboxy-terminal alanine and threonine residues (CAT tails). Failure to degrade CAT-tailed proteins disrupts global protein homeostasis, as CAT-tailed proteins aggregate and sequester chaperones. Why cells employ such a potentially toxic process during RQC is unclear. Here, we developed quantitative techniques to assess how CAT tails affect stalled polypeptide degradation in Saccharomyces cerevisiae. We found that CAT tails improve Ltn1’s efficiency in targeting structured polypeptides, which are otherwise poor Ltn1 substrates. If Ltn1 fails, CAT tails undergo a backup route of ubiquitylation off the ribosome, mediated by the ubiquitin ligase Hul5. Thus, CAT tails functionalize the carboxy-termini of stalled polypeptides to drive their degradation on and off the ribosome.

scholarly journals Aggregation of CAT tails blocks their degradation and causes proteotoxicity in S. cerevisiae

2019 ◽  
Author(s):  
Cole S. Sitron ◽  
Joseph H. Park ◽  
Jenna M. Giafaglione ◽  
Onn Brandman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quality Control ◽  
Ribosomal Subunit ◽  
E3 Ligase ◽  
Protein Homeostasis ◽  
Large Ribosomal Subunit ◽  
Proteotoxic Stress ◽  
Chemical Tools ◽  
Carboxy Terminal

AbstractThe Ribosome-associated Quality Control (RQC) pathway co-translationally marks incomplete polypeptides from stalled translation with two signals that trigger their proteasome-mediated degradation. The E3 ligase Ltn1 adds ubiquitin and Rqc2 directs the large ribosomal subunit to append carboxy-terminal alanine and threonine residues (CAT tails). When excessive amounts of incomplete polypeptides evade Ltn1, CAT-tailed proteins accumulate and can self-associate into aggregates. CAT tail aggregation has been hypothesized to either protect cells by sequestering potentially toxic incomplete polypeptides or harm cells by disrupting protein homeostasis. To distinguish between these possibilities, we modulated CAT tail aggregation in Saccharomyces cerevisiae with genetic and chemical tools to analyze CAT tails in aggregated and un-aggregated states. We found that enhancing CAT tail aggregation induces proteotoxic stress and antagonizes degradation of CAT-tailed proteins, while inhibiting aggregation reverses these effects. Our findings suggest that CAT tail aggregation harms RQC-compromised cells and that preventing aggregation can mitigate this toxicity.

High levels of the mitochondrial large ribosomal subunit protein 40 prevent loss of mitochondrial DNA in nullmmf1 Saccharomyces cerevisiae cells

Yeast ◽  
2004 ◽  
Vol 21 (7) ◽  
pp. 539-548 ◽  
Author(s):  
Rosita Accardi ◽  
Ellinor Oxelmark ◽  
Nicolas Jauniaux ◽  
Vito de Pinto ◽  
Antonio Marchini ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Ribosomal Subunit ◽  
Large Ribosomal Subunit ◽  
Subunit Protein ◽  
Ribosomal Subunit Protein

scholarly journals The Putative RNA Helicase Dbp6p Functionally Interacts With Rpl3p, Nop8p and the Novel trans-acting Factor Rsa3p During Biogenesis of 60S Ribosomal Subunits in Saccharomyces cerevisiae

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1687-1699
Author(s):  
Jesús de la Cruz ◽  
Thierry Lacombe ◽  
Olivier Deloche ◽  
Patrick Linder ◽  
Dieter Kressler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosome Biogenesis ◽  
Null Allele ◽  
Ribosomal Subunit ◽  
Interaction Network ◽  
The Novel ◽  
Rna Helicases ◽  
Ribosomal Subunits ◽  
Synthetic Lethal ◽  
Synthetically Lethal

Abstract Ribosome biogenesis requires at least 18 putative ATP-dependent RNA helicases in Saccharomyces cerevisiae. To explore the functional environment of one of these putative RNA helicases, Dbp6p, we have performed a synthetic lethal screen with dbp6 alleles. We have previously characterized the nonessential Rsa1p, whose null allele is synthetically lethal with dbp6 alleles. Here, we report on the characterization of the four remaining synthetic lethal mutants, which reveals that Dbp6p also functionally interacts with Rpl3p, Nop8p, and the so-far-uncharacterized Rsa3p (ribosome assembly 3). The nonessential Rsa3p is a predominantly nucleolar protein required for optimal biogenesis of 60S ribosomal subunits. Both Dbp6p and Rsa3p are associated with complexes that most likely correspond to early pre-60S ribosomal particles. Moreover, Rsa3p is co-immunoprecipitated with protA-tagged Dbp6p under low salt conditions. In addition, we have established a synthetic interaction network among factors involved in different aspects of 60S-ribosomal-subunit biogenesis. This extensive genetic analysis reveals that the rsa3 null mutant displays some specificity by being synthetically lethal with dbp6 alleles and by showing some synthetic enhancement with the nop8-101 and the rsa1 null allele.

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