scholarly journals SSB, Encoding a Ribosome-Associated Chaperone, Is Coordinately Regulated with Ribosomal Protein Genes

1999 ◽  
Vol 181 (10) ◽  
pp. 3136-3143 ◽  
Author(s):  
Nelson Lopez ◽  
John Halladay ◽  
William Walter ◽  
Elizabeth A. Craig
Keyword(s):  
Heat Shock ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Chain Complex ◽  
Mrna Levels ◽  
Ribosomal Protein Genes ◽  
Genes Encoding ◽  
Synthetic Capacity ◽  
Translational Apparatus ◽  
Temperature Upshift

ABSTRACT Genes encoding ribosomal proteins and other components of the translational apparatus are coregulated to efficiently adjust the protein synthetic capacity of the cell. Ssb, a Saccharomyces cerevisiae Hsp70 cytosolic molecular chaperone, is associated with the ribosome-nascent chain complex. To determine whether this chaperone is coregulated with ribosomal proteins, we studied the mRNA regulation of SSB under several environmental conditions. Ssb and the ribosomal protein rpL5 mRNAs were up-regulated upon carbon upshift and down-regulated upon amino acid limitation, unlike the mRNA of another cytosolic Hsp70, Ssa. Ribosomal protein and Ssb mRNAs, like many mRNAs, are down-regulated upon a rapid temperature upshift. The mRNA reduction of several ribosomal protein genes and Ssb was delayed by the presence of an allele, EXA3-1, of the gene encoding the heat shock factor (HSF). However, upon a heat shock theEXA3-1 mutation did not significantly alter the reduction in the mRNA levels of two genes encoding proteins unrelated to the translational apparatus. Analysis of gene fusions indicated that the transcribed region, but not the promoter of SSB, is sufficient for this HSF-dependent regulation. Our studies suggest that Ssb is regulated like a core component of the ribosome and that HSF is required for proper regulation of SSB and ribosomal mRNA after a temperature upshift.

scholarly journals Sporulation and rna2 lower ribosomal protein mRNA levels by different mechanisms in Saccharomyces cerevisiae.

1982 ◽  
Vol 2 (10) ◽  
pp. 1199-1204 ◽  
Author(s):  
E Kraig ◽  
J E Haber ◽  
M Rosbash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Relative Rate ◽  
Synthesis Rate ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mrna Levels ◽  
Ribosomal Protein Genes ◽  
Mrna Metabolism

In Saccharomyces cerevisiae, the levels of ribosomal protein mRNAs are regulated coordinately. Vegetative strains carrying the temperature-sensitive rna2 mutation exhibit a dramatic decrease in the levels of most ribosomal protein mRNAs at the restrictive temperature. Similarly, in wild-type cells induced to sporulate by nitrogen starvation, there is a fivefold reduction in the relative synthesis rate of ribosomal proteins. Using Northern gel analysis and cloned ribosomal protein genes, we compared the way in which ribosomal protein mRNA is affected under these two conditions. In vegetative rna2 cells, incubation at 34 degrees C led to the disappearance of ribosomal protein mRNAs and the accumulation of higher-molecular-weight precursor RNAs. A different phenotype was observed during sporulation. Although sporulating conditions led to a significant reduction in the relative abundance of ribosomal protein mRNA, there was no detectable accumulation of precursor RNAs even in rna2/rna2 diploids at 34 degrees C. A suppressor of rna2 and of other rna mutations, SRN1, at least partially relieved the block in the splicing of the ribosomal protein 51 intron in vegetative rna2 cells but did not detectably affect the level of ribosomal protein mRNA in sporulating cells. We concluded that the rna2 mutation and sporulation conditions affected ribosomal protein mRNA metabolism in two quite different ways. In vegetative cells the mutant rna2 effected a block which occurred primarily in post-transcriptional processing, whereas in sporulating cells the ribosomal protein mRNA levels were decreased by some other mechanism, presumably a change in the relative rate of transcription or mRNA turnover. Furthermore, the data suggest that the mutation rna2 has no additional effect on ribosomal protein mRNA metabolism in sporulating cells.

scholarly journals Ribosomal protein imbalance launches a C/EBP-based program to preserve tissue integrity

2018 ◽  
Author(s):  
Ludovic Baillon
Keyword(s):  
Ribosomal Protein ◽  
Genomic Instability ◽  
Ribosomal Proteins ◽  
Molecular Model ◽  
Ribosomal Protein Genes ◽  
Cell Competition ◽  
Tissue Integrity ◽  
Enhancer Binding Protein ◽  
Genes Encoding ◽  
Number Variation

SummaryGenes encoding ribosomal proteins are expressed at rate limiting levels, rendering their biological function highly sensitive to the copy-number variation that results from genomic instability. Cells with a reduced number of ribosomal protein genes (RPGs) are eliminated, when intermingled with wild type cells, via a process known as cell competition. The mechanisms underlying this phenomenon are poorly understood. Here we report the function of a CCAAT-Enhancer-Binding Protein (C/EBP), Xrp1, that is critically required for the elimination of cells with a hemizygous RPG genotype. In such cells, Xrp1 is transcriptionally upregulated by an autoregulatory loop and is able to trigger cell elimination. Since genomic instability is likely to cause the loss of a haploinsufficient RPG, we propose a molecular model of how RPGs, together with a C/EBP-dependent transcriptional program, could preserve the genomic integrity of tissues.

Sporulation and rna2 lower ribosomal protein mRNA levels by different mechanisms in Saccharomyces cerevisiae

1982 ◽  
Vol 2 (10) ◽  
pp. 1199-1204
Author(s):  
E Kraig ◽  
J E Haber ◽  
M Rosbash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Relative Rate ◽  
Synthesis Rate ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mrna Levels ◽  
Ribosomal Protein Genes ◽  
Mrna Metabolism

In Saccharomyces cerevisiae, the levels of ribosomal protein mRNAs are regulated coordinately. Vegetative strains carrying the temperature-sensitive rna2 mutation exhibit a dramatic decrease in the levels of most ribosomal protein mRNAs at the restrictive temperature. Similarly, in wild-type cells induced to sporulate by nitrogen starvation, there is a fivefold reduction in the relative synthesis rate of ribosomal proteins. Using Northern gel analysis and cloned ribosomal protein genes, we compared the way in which ribosomal protein mRNA is affected under these two conditions. In vegetative rna2 cells, incubation at 34 degrees C led to the disappearance of ribosomal protein mRNAs and the accumulation of higher-molecular-weight precursor RNAs. A different phenotype was observed during sporulation. Although sporulating conditions led to a significant reduction in the relative abundance of ribosomal protein mRNA, there was no detectable accumulation of precursor RNAs even in rna2/rna2 diploids at 34 degrees C. A suppressor of rna2 and of other rna mutations, SRN1, at least partially relieved the block in the splicing of the ribosomal protein 51 intron in vegetative rna2 cells but did not detectably affect the level of ribosomal protein mRNA in sporulating cells. We concluded that the rna2 mutation and sporulation conditions affected ribosomal protein mRNA metabolism in two quite different ways. In vegetative cells the mutant rna2 effected a block which occurred primarily in post-transcriptional processing, whereas in sporulating cells the ribosomal protein mRNA levels were decreased by some other mechanism, presumably a change in the relative rate of transcription or mRNA turnover. Furthermore, the data suggest that the mutation rna2 has no additional effect on ribosomal protein mRNA metabolism in sporulating cells.

Characterization of Arabidopsis thaliana lines with T-DNA insertions in the mitochondrial ribosomal protein genes Rps14 and Rps19

2019 ◽  
Vol 79 (02) ◽  
Author(s):  
Suman Lata ◽  
Anshul Watts ◽  
S. R. Bhat
Keyword(s):  
Arabidopsis Thaliana ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Ribosomal Protein Genes ◽  
Protein Coding ◽  
Mitochondrial Ribosomal Protein ◽  
Genes Encoding ◽  
Coordinated Expression ◽  
Dna Insertion ◽  
Mutant Lines

In Arabidopsis, most of the genes encoding mitochondrial ribosomal proteins are located in the nucleus and only seven are present in the mitochondrial genome. Assembly of a functional ribosome requires coordinated expression of ribosomal protein encoding genes located in both these organelles. Genes and promoters of nuclear encoded mitochondrial ribosomal protein coding genes of plants have not been well characterized so far. In the present study we have characterized Arabidopsis thaliana SALK mutant lines with T-DNA insertion in Rps14 or Rps19 gene. The location of T-DNA insertion in the mutant lines was confirmed and plants homozygous and hemizygous for TDNA insertion were identified for both Rps14 and Rps19 genes. In homozygous T-DNA mutant lines of both Rps14 and Rps19 genes, the expression was estimated using RTPCR. Rps14 and Rps19 transcripts similar to wild type were present in homozygous mutant plants of Rps14 and Rps19 which indicated that T-DNA insertion has not affected their expression.

scholarly journals Structure and expression of the Saccharomyces cerevisiae CRY1 gene: a highly conserved ribosomal protein gene

1987 ◽  
Vol 7 (5) ◽  
pp. 1764-1775
Author(s):  
J C Larkin ◽  
J R Thompson ◽  
J L Woolford
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Heat Shock ◽  
Ribosomal Protein ◽  
Promoter Element ◽  
Consensus Sequences ◽  
Genes Encoding ◽  
Yeast Genes ◽  
Translational Apparatus ◽  
Cry1 Gene

The Saccharomyces cerevisiae CRY1 gene encodes ribosomal protein rp59, a component of the 40S ribosomal subunit. Mutations in CRY1 can confer resistance to the alkaloid cryptopleurine, an inhibitor of the elongation step of translation. The nucleotide sequence of the cloned CRY1 gene was determined. The predicted amino acid sequence shows that CRY1 encodes a 14,561-dalton polypeptide that has 88% amino acid sequence homology to the hamster or human S14 ribosomal protein responsible for emetine resistance and 45% homology to Escherichia coli ribosomal protein S11. Analysis of the DNA sequences upstream from CRY1 revealed the presence of three sequences, HOMOL1 (consensus, A/TACATCC/TG/ATA/GCA), RPG (consensus, ACCCA/GTACATT/CT/A), and a thymine-rich sequence, found upstream of more than 20 other cloned yeast genes encoding components of the translational apparatus. We exploited the ability to assay the expression of CRY1 in vivo by using the cryptopleurine resistance phenotype to demonstrate that these three consensus sequences are necessary for the transcription of CRY1. We previously showed that the upstream promoter element of the yeast RP39A gene consists of these identical sequence motifs. Therefore, we suggest that these three sequences define a consensus promoter element for the genes encoding the yeast translational apparatus. CRY1 is one of several hundred yeast genes, including ribosomal protein genes, whose expression is transiently decreased 10-fold upon heat shock. We found that the HOMOL1 and RPG consensus sequences are not necessary for the heat shock response of CRY1.

scholarly journals Structure and expression of the Saccharomyces cerevisiae CRY1 gene: a highly conserved ribosomal protein gene.

1987 ◽  
Vol 7 (5) ◽  
pp. 1764-1775 ◽  
Author(s):  
J C Larkin ◽  
J R Thompson ◽  
J L Woolford
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Heat Shock ◽  
Ribosomal Protein ◽  
Promoter Element ◽  
Consensus Sequences ◽  
Genes Encoding ◽  
Yeast Genes ◽  
Translational Apparatus ◽  
Cry1 Gene

The Saccharomyces cerevisiae CRY1 gene encodes ribosomal protein rp59, a component of the 40S ribosomal subunit. Mutations in CRY1 can confer resistance to the alkaloid cryptopleurine, an inhibitor of the elongation step of translation. The nucleotide sequence of the cloned CRY1 gene was determined. The predicted amino acid sequence shows that CRY1 encodes a 14,561-dalton polypeptide that has 88% amino acid sequence homology to the hamster or human S14 ribosomal protein responsible for emetine resistance and 45% homology to Escherichia coli ribosomal protein S11. Analysis of the DNA sequences upstream from CRY1 revealed the presence of three sequences, HOMOL1 (consensus, A/TACATCC/TG/ATA/GCA), RPG (consensus, ACCCA/GTACATT/CT/A), and a thymine-rich sequence, found upstream of more than 20 other cloned yeast genes encoding components of the translational apparatus. We exploited the ability to assay the expression of CRY1 in vivo by using the cryptopleurine resistance phenotype to demonstrate that these three consensus sequences are necessary for the transcription of CRY1. We previously showed that the upstream promoter element of the yeast RP39A gene consists of these identical sequence motifs. Therefore, we suggest that these three sequences define a consensus promoter element for the genes encoding the yeast translational apparatus. CRY1 is one of several hundred yeast genes, including ribosomal protein genes, whose expression is transiently decreased 10-fold upon heat shock. We found that the HOMOL1 and RPG consensus sequences are not necessary for the heat shock response of CRY1.

Mild temperature shock alters the transcription of a discrete class of Saccharomyces cerevisiae genes

1983 ◽  
Vol 3 (3) ◽  
pp. 457-465
Author(s):  
C H Kim ◽  
J R Warner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Temperature Shift ◽  
Restrictive Temperature ◽  
Ribosomal Protein Genes ◽  
Wild Type ◽  
Temperature Shock ◽  
Mild Temperature ◽  
Mutant Cells

In Saccharomyces cerevisiae the synthesis of ribosomal proteins declines temporarily after a culture has been subjected to a mild temperature shock, i.e., a shift from 23 to 36 degrees C, each of which support growth. Using cloned genes for several S. cerevisiae ribosomal proteins, we found that the changes in the synthesis of ribosomal proteins parallel the changes in the concentration of mRNA of each. The disappearance and reappearance of the mRNA is due to a brief but severe inhibition of the transcription of each of the ribosomal protein genes, although the total transcription of mRNA in the cells is relatively unaffected by the temperature shock. The precisely coordinated response of these genes, which are scattered throughout the genome, suggests that either they or the enzyme which transcribes them has unique properties. In certain S. cerevisiae mutants, the synthesis of ribosomal proteins never recovers from a temperature shift. Yet both the decline and the resumption of transcription of these genes during the 30 min after the temperature shift are indistinguishable from those in wild-type cells. The failure of the mutant cells to grow at the restrictive temperature appears to be due to their inability to process the RNA transcribed from genes which have introns (Rosbash et al., Cell 24:679-686, 1981), a large proportion of which appear to be ribosomal protein genes.

scholarly journals The yeast omnipotent suppressor SUP46 encodes a ribosomal protein which is a functional and structural homolog of the Escherichia coli S4 ram protein.

Genetics ◽  
1992 ◽  
Vol 132 (2) ◽  
pp. 375-386 ◽  
Author(s):  
A Vincent ◽  
S W Liebman
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Protein ◽  
Dna Sequences ◽  
Ribosomal Proteins ◽  
Amino Acid Sequences ◽  
Ribosomal Protein Genes ◽  
Significant Homology ◽  
A Cell ◽  
Functional Equivalent ◽  
Ribosomal Protein S13

Abstract The accurate synthesis of proteins is crucial to the existence of a cell. In yeast, several genes that affect the fidelity of translation have been identified (e.g., omnipotent suppressors, antisuppressors and allosuppressors). We have found that the dominant omnipotent suppressor SUP46 encodes the yeast ribosomal protein S13. S13 is encoded by two similar genes, but only the sup46 copy of the gene is able to fully complement the recessive phenotypes of SUP46 mutations. Both copies of the S13 genes contain introns. Unlike the introns of other duplicated ribosomal protein genes which are highly diverged, the duplicated S13 genes have two nearly identical DNA sequences of 25 and 31 bp in length within their introns. The SUP46 protein has significant homology to the S4 ribosomal protein in prokaryotic-type ribosomes. S4 is encoded by one of the ram (ribosomal ambiguity) genes in Escherichia coli which are the functional equivalent of omnipotent suppressors in yeast. Thus, SUP46 and S4 demonstrate functional as well as sequence conservation between prokaryotic and eukaryotic ribosomal proteins. SUP46 and S4 are most similar in their central amino acid sequences. Interestingly, the alterations resulting from the SUP46 mutations and the segment of the S4 protein involved in binding to the 16S rRNA are within this most conserved region.

scholarly journals Dedicated chaperones coordinate co-translational regulation of ribosomal protein production with ribosome assembly to preserve proteostasis

2021 ◽  
Author(s):  
Benjamin Pillet ◽  
Alfonso Méndez-Godoy ◽  
Guillaume Murat ◽  
Sébastien Favre ◽  
Michael Stumpe ◽  
...  
Keyword(s):  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Translational Regulation ◽  
De Novo ◽  
Spatial Separation ◽  
Ribosome Assembly ◽  
Mrna Levels ◽  
Ribosomal Assembly ◽  
Surplus Production ◽  
Regulatory Machinery

AbstractThe biogenesis of eukaryotic ribosomes involves the ordered assembly of around 80 ribosomal proteins. Supplying equimolar amounts of assembly-competent ribosomal proteins is complicated by their aggregation propensity and the spatial separation of their location of synthesis and pre-ribosome incorporation. Recent evidence has highlighted that dedicated chaperones protect individual, unassembled ribosomal proteins on their path to the pre-ribosomal assembly site. Here, we show that the co-translational recognition of Rpl3 and Rpl4 by their respective dedicated chaperone, Rrb1 or Acl4, prevents the degradation of the encoding RPL3 and RPL4 mRNAs in the yeast Saccharomyces cerevisiae. In both cases, negative regulation of mRNA levels occurs when the availability of the dedicated chaperone is limited and the nascent ribosomal protein is instead accessible to a regulatory machinery consisting of the nascent-polypeptide associated complex and the Caf130-associated Ccr4-Not complex. Notably, deregulated expression of Rpl3 and Rpl4 leads to their massive aggregation and a perturbation of overall proteostasis in cells lacking the E3 ubiquitin ligase Tom1. Taken together, we have uncovered an unprecedented regulatory mechanism that adjusts the de novo synthesis of Rpl3 and Rpl4 to their actual consumption during ribosome assembly and, thereby, protects cells from the potentially detrimental effects of their surplus production.

scholarly journals Continued functioning of the secretory pathway is essential for ribosome synthesis.

1994 ◽  
Vol 14 (4) ◽  
pp. 2493-2502 ◽  
Author(s):  
K Mizuta ◽  
J R Warner
Keyword(s):  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Secretory Pathway ◽  
Regulatory Elements ◽  
Carboxypeptidase Y ◽  
Temperature Sensitive ◽  
Mrna Levels ◽  
Nonpermissive Temperature ◽  
Ribosome Synthesis ◽  
Secretion Pathway

To explore the regulatory elements that maintain the balanced synthesis of the components of the ribosome, we isolated a temperature-sensitive (ts) mutant of Saccharomyces cerevisiae in which transcription both of rRNA and of ribosomal protein genes is defective at the nonpermissive temperature. Temperature sensitivity for growth is recessive and segregates 2:2. A gene that complements the ts phenotype was cloned from a genomic DNA library. Sequence analysis revealed that this gene is SLY1, encoding a protein essential for protein and vesicle transport between the endoplasmic reticulum and the Golgi apparatus. In the strain carrying our ts allele of SLY1, accumulation of the carboxypeptidase Y precursor was detected at the nonpermissive temperature, indicating that the secretory pathway is defective. To ask whether the effect of the ts allele on ribosome synthesis was specific for sly1 or was a general result of the inactivation of the secretion pathway, we assayed the levels of mRNA for several ribosomal proteins in cells carrying ts alleles of sec1, sec7, sec11, sec14, sec18, sec53, or sec63, representing all stages of secretion. In each case, the mRNA levels were severely depressed, suggesting that this is a common feature in mutants of protein secretion. For the mutants tested, transcription of rRNA was also substantially reduced. Furthermore, treatment of a sensitive strain with brefeldin A at a concentration sufficient to block the secretion pathway also led to a decrease of the level of ribosomal protein mRNA, with kinetics suggesting that the effect of a secretion defect is manifest within 15 to 30 min. We conclude that the continued function of the entire secretion pathway is essential for the maintenance of ribosome synthesis. The apparent coupling of membrane synthesis and ribosome synthesis suggest the existence of a regulatory network that connects the production of the various structural elements of the cell.

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