scholarly journals Mechanisms Coordinating Ribosomal Protein Gene Transcription in Response to Stress

2020 ◽  
Author(s):  
Sevil Zencir ◽  
Daniel Dilg ◽  
Maria Paula Rueda ◽  
David Shore ◽  
Benjamin Albert

AbstractWhile expression of ribosomal protein genes (RPGs) in the budding yeast Saccharomyces cerevisiae has been extensively studied, a longstanding enigma persists regarding their co-regulation under fluctuating nutrient and stress conditions. Most (<90%) of RPG promoters display one of two distinct arrangements of a core set of transcription factors (TFs; Rap1, Fhl1 and Ifh1) and are further differentiated by the presence or absence of the HMGB box protein Hmo1. However, a third group of promoters appears not to bind any of these proteins, raising the question of how the whole suite of genes is co-regulated. We demonstrate that all RPGs are regulated by two distinct, but complementary mechanisms driven by the TFs Ifh1 and Sfp1, both of which are required for maximal expression in optimal conditions and coordinated down-regulation upon stress. At the majority of RPG promoters Ifh1-dependent regulation predominates, whereas Sfp1 plays the major role at all other genes. We also uncovered an unexpected, protein homeostasis-dependent binding property of Hmo1 at a large subset of RPG promoters. Finally, we show that the Ifh1 paralog Crf1, previously described as a transcriptional repressor, can act as a constitutive RPG activator in the W303 strain background when overexpressed. Our study thus provides a more complete picture of RPG regulation and may serve as a paradigm for unravelling RPG regulation in multicellular eukaryotes.

2020 ◽  
Vol 48 (20) ◽  
pp. 11408-11420 ◽  
Author(s):  
Sevil Zencir ◽  
Daniel Dilg ◽  
Maria Paula Rueda ◽  
David Shore ◽  
Benjamin Albert

Abstract While expression of ribosomal protein genes (RPGs) in the budding yeast has been extensively studied, a longstanding enigma persists regarding their co-regulation under fluctuating growth conditions. Most RPG promoters display one of two distinct arrangements of a core set of transcription factors (TFs) and are further differentiated by the presence or absence of the HMGB protein Hmo1. However, a third group of promoters appears not to be bound by any of these proteins, raising the question of how the whole suite of genes is co-regulated. We demonstrate here that all RPGs are regulated by two distinct, but complementary mechanisms driven by the TFs Ifh1 and Sfp1, both of which are required for maximal expression in optimal conditions and coordinated downregulation upon stress. At the majority of RPG promoters, Ifh1-dependent regulation predominates, whereas Sfp1 plays the major role at all other genes. We also uncovered an unexpected protein homeostasis-dependent binding property of Hmo1 at RPG promoters. Finally, we show that the Ifh1 paralog Crf1, previously described as a transcriptional repressor, can act as a constitutive RPG activator. Our study provides a more complete picture of RPG regulation and may serve as a paradigm for unravelling RPG regulation in multicellular eukaryotes.


1991 ◽  
Vol 11 (5) ◽  
pp. 2723-2735 ◽  
Author(s):  
C M Moehle ◽  
A G Hinnebusch

An amino acid limitation in bacteria elicits a global response, called stringent control, that leads to reduced synthesis of rRNA and ribosomal proteins and increased expression of amino acid biosynthetic operons. We have used the antimetabolite 3-amino-1,2,4-triazole to cause histidine limitation as a means to elicit the stringent response in the yeast Saccharomyces cerevisiae. Fusions of the yeast ribosomal protein genes RPL16A, CRY1, RPS16A, and RPL25 with the Escherichia coli lacZ gene were used to show that the expression of these genes is reduced by a factor of 2 to 5 during histidine-limited exponential growth and that this regulation occurs at the level of transcription. Stringent regulation of the four yeast ribosomal protein genes was shown to be associated with a nucleotide sequence, known as the UASrpg (upstream activating sequence for ribosomal protein genes), that binds the transcriptional regulatory protein RAP1. The RAP1 binding sites also appeared to mediate the greater ribosomal protein gene expression observed in cells growing exponentially than in cells in stationary phase. Although expression of the ribosomal protein genes was reduced in response to histidine limitation, the level of RAP1 DNA-binding activity in cell extracts was unaffected. Yeast strains bearing a mutation in any one of the genes GCN1 to GCN4 are defective in derepression of amino acid biosynthetic genes in 10 different pathways under conditions of histidine limitation. These Gcn- mutants showed wild-type regulation of ribosomal protein gene expression, which suggests that separate regulatory pathways exist in S. cerevisiae for the derepression of amino acid biosynthetic genes and the repression of ribosomal protein genes in response to amino acid starvation.


Blood ◽  
2011 ◽  
Vol 118 (26) ◽  
pp. 6943-6951 ◽  
Author(s):  
Jason E. Farrar ◽  
Adrianna Vlachos ◽  
Eva Atsidaftos ◽  
Hannah Carlson-Donohoe ◽  
Thomas C. Markello ◽  
...  

Abstract Diamond-Blackfan anemia (DBA) is a congenital BM failure syndrome characterized by hypoproliferative anemia, associated physical abnormalities, and a predisposition to cancer. Perturbations of the ribosome appear to be critically important in DBA; alterations in 9 different ribosomal protein genes have been identified in multiple unrelated families, along with rarer abnormalities of additional ribosomal proteins. However, at present, only 50% to 60% of patients have an identifiable genetic lesion by ribosomal protein gene sequencing. Using genome-wide single-nucleotide polymorphism array to evaluate for regions of recurrent copy variation, we identified deletions at known DBA-related ribosomal protein gene loci in 17% (9 of 51) of patients without an identifiable mutation, including RPS19, RPS17, RPS26, and RPL35A. No recurrent regions of copy variation at novel loci were identified. Because RPS17 is a duplicated gene with 4 copies in a diploid genome, we demonstrate haploinsufficient RPS17 expression and a small subunit ribosomal RNA processing abnormality in patients harboring RPS17 deletions. Finally, we report the novel identification of variable mosaic loss involving known DBA gene regions in 3 patients from 2 kindreds. These data suggest that ribosomal protein gene deletion is more common than previously suspected and should be considered a component of the initial genetic evaluation in cases of suspected DBA.


1988 ◽  
Vol 8 (10) ◽  
pp. 4328-4341 ◽  
Author(s):  
K G Hamil ◽  
H G Nam ◽  
H M Fried

The DNA sequence UAST (TCGTTTTGTACGTTTTTCA) was found to mediate transcription of yeast ribosomal protein gene TCM1. UAST was defined as a transcriptional activator on the basis of loss of transcription accompanying deletions of all or part of UAST, orientation-independent restoration of transcription promoted by a synthetic UAST oligomer inserted either into TCM1 or into the yeast CYC1 gene lacking its transcriptional activation region, and diminished transcription following nucleotide alterations in UAST. UAST bound in vitro to a protein denoted TAF (TCM1 activation factor); TAF was concluded to be a transcriptional activator protein because nucleotide alterations in UAST that diminished transcription in vivo also diminished TAF binding in vitro. The sequence of UAST bore no obvious resemblance to UASrpg, the principal cis-acting element common to most yeast ribosomal protein genes. Likewise, TAF was distinguished from the UASrpg-binding protein TUF, since (i) TAF and TUF were chromatographically separable, (ii) binding of either TAF or TUF to its corresponding UAS was unaffected by an excess of UASrpg or UAST DNA, respectively, and (iii) photochemical cross-linking experiments showed that TAF was a protein of 147 kilodaltons (kDa), while TUF was detected as an approximately 120-kDa polypeptide, consistent with its known size. Cross-linking experiments also revealed that both UAST and UASrpg bound a second heretofore unobserved 82-kDa protein; binding of this additional protein appeared to require binding of TAF or TUF. On the basis of the biochemical characterization of TAF and a lack of sequence similarity between UAST and UASrpg, we suggest that transcription of TCM1 is mediated by a cis-acting sequence and at least one trans-acting factor different from the elements which promote transcription of most other ribosomal protein genes. A second trans-acting factor may be shared by TCM1 and other ribosomal protein genes; this factor could mediate coordinate regulation of these genes.


2015 ◽  
Vol 35 (17) ◽  
pp. 2947-2964 ◽  
Author(s):  
Bhawana Uprety ◽  
Rwik Sen ◽  
Sukesh R. Bhaumik

NuA4 (nucleosome acetyltransferase of H4) promotes transcriptional initiation of TFIID (a complex of TBP and TBP-associated factors [TAFs])-dependent ribosomal protein genes involved in ribosome biogenesis. However, it is not clearly understood how NuA4 regulates the transcription of ribosomal protein genes. Here, we show that NuA4 is recruited to the promoters of ribosomal protein genes, such asRPS5,RPL2B, andRPS11B, for TFIID recruitment to initiate transcription, and the recruitment of NuA4 to these promoters is impaired in the absence of its Eaf1p component. Intriguingly, impaired NuA4 recruitment in aΔeaf1strain depletes recruitment of TFIID (a TAF-dependent form of TBP) but not the TAF-independent form of TBP to the promoters of ribosomal protein genes. However, in the absence of NuA4, SAGA (Spt-Ada-Gcn5-acetyltransferase) is involved in targeting the TAF-independent form of TBP to the promoters of ribosomal protein genes for transcriptional initiation. Thus, NuA4 plays an important role in targeting TFIID to the promoters of ribosomal protein genes for transcriptional initiationin vivo. Such a function is mediated via its targeted histone acetyltransferase activity. In the absence of NuA4, ribosomal protein genes lose TFIID dependency and become SAGA dependent for transcriptional initiation. Collectively, these results provide significant insights into the regulation of ribosomal protein gene expression and, hence, ribosome biogenesis and functions.


1990 ◽  
Vol 10 (6) ◽  
pp. 3284-3288
Author(s):  
D Perelman ◽  
J C Boothroyd

Introns are almost always present in ribosomal protein genes, even in organisms in which introns are rare. Although trans spliced, the trypanosome ribosomal protein gene S14 apparently does not have cis introns, which supports the notion that such introns are absent in this organism.


1991 ◽  
Vol 11 (5) ◽  
pp. 2723-2735 ◽  
Author(s):  
C M Moehle ◽  
A G Hinnebusch

An amino acid limitation in bacteria elicits a global response, called stringent control, that leads to reduced synthesis of rRNA and ribosomal proteins and increased expression of amino acid biosynthetic operons. We have used the antimetabolite 3-amino-1,2,4-triazole to cause histidine limitation as a means to elicit the stringent response in the yeast Saccharomyces cerevisiae. Fusions of the yeast ribosomal protein genes RPL16A, CRY1, RPS16A, and RPL25 with the Escherichia coli lacZ gene were used to show that the expression of these genes is reduced by a factor of 2 to 5 during histidine-limited exponential growth and that this regulation occurs at the level of transcription. Stringent regulation of the four yeast ribosomal protein genes was shown to be associated with a nucleotide sequence, known as the UASrpg (upstream activating sequence for ribosomal protein genes), that binds the transcriptional regulatory protein RAP1. The RAP1 binding sites also appeared to mediate the greater ribosomal protein gene expression observed in cells growing exponentially than in cells in stationary phase. Although expression of the ribosomal protein genes was reduced in response to histidine limitation, the level of RAP1 DNA-binding activity in cell extracts was unaffected. Yeast strains bearing a mutation in any one of the genes GCN1 to GCN4 are defective in derepression of amino acid biosynthetic genes in 10 different pathways under conditions of histidine limitation. These Gcn- mutants showed wild-type regulation of ribosomal protein gene expression, which suggests that separate regulatory pathways exist in S. cerevisiae for the derepression of amino acid biosynthetic genes and the repression of ribosomal protein genes in response to amino acid starvation.


1988 ◽  
Vol 8 (10) ◽  
pp. 4328-4341
Author(s):  
K G Hamil ◽  
H G Nam ◽  
H M Fried

The DNA sequence UAST (TCGTTTTGTACGTTTTTCA) was found to mediate transcription of yeast ribosomal protein gene TCM1. UAST was defined as a transcriptional activator on the basis of loss of transcription accompanying deletions of all or part of UAST, orientation-independent restoration of transcription promoted by a synthetic UAST oligomer inserted either into TCM1 or into the yeast CYC1 gene lacking its transcriptional activation region, and diminished transcription following nucleotide alterations in UAST. UAST bound in vitro to a protein denoted TAF (TCM1 activation factor); TAF was concluded to be a transcriptional activator protein because nucleotide alterations in UAST that diminished transcription in vivo also diminished TAF binding in vitro. The sequence of UAST bore no obvious resemblance to UASrpg, the principal cis-acting element common to most yeast ribosomal protein genes. Likewise, TAF was distinguished from the UASrpg-binding protein TUF, since (i) TAF and TUF were chromatographically separable, (ii) binding of either TAF or TUF to its corresponding UAS was unaffected by an excess of UASrpg or UAST DNA, respectively, and (iii) photochemical cross-linking experiments showed that TAF was a protein of 147 kilodaltons (kDa), while TUF was detected as an approximately 120-kDa polypeptide, consistent with its known size. Cross-linking experiments also revealed that both UAST and UASrpg bound a second heretofore unobserved 82-kDa protein; binding of this additional protein appeared to require binding of TAF or TUF. On the basis of the biochemical characterization of TAF and a lack of sequence similarity between UAST and UASrpg, we suggest that transcription of TCM1 is mediated by a cis-acting sequence and at least one trans-acting factor different from the elements which promote transcription of most other ribosomal protein genes. A second trans-acting factor may be shared by TCM1 and other ribosomal protein genes; this factor could mediate coordinate regulation of these genes.


1990 ◽  
Vol 10 (6) ◽  
pp. 3284-3288 ◽  
Author(s):  
D Perelman ◽  
J C Boothroyd

Introns are almost always present in ribosomal protein genes, even in organisms in which introns are rare. Although trans spliced, the trypanosome ribosomal protein gene S14 apparently does not have cis introns, which supports the notion that such introns are absent in this organism.


1986 ◽  
Vol 6 (2) ◽  
pp. 674-687
Author(s):  
M O Rotenberg ◽  
J L Woolford

To initiate a genetic analysis of yeast ribosomal protein gene promoters, we have constructed a gene fusion between the yeast ribosomal protein gene RP39A and the Escherichia coli lacZ gene. This gene fusion contains approximately 1,030 nucleotides of the 5' flanking region and the first 49 1/3 codons of RP39A fused in frame to a large 3' end fragment of lacZ. Whether it is introduced into yeast cells on a moderately high-copy-number plasmid, or integrated into the yeast genome at the RP39A locus, this RP39A-lacZ gene directs the synthesis of a hybrid transcript which encodes beta-galactosidase activity. Deletions in the 5' flanking region of RP39A-lacZ were constructed by linker insertion and BAL 31 mutagenesis. The expression of the mutant genes in yeast cells was assayed by measuring RP39A-lacZ mRNA and beta-galactosidase levels. By these means we have shown that the sequences between nucleotides -256 and -170 upstream of RP39A are essential for expression of this gene. Three sequence motifs, HOMOL1, RPG, and a T-rich region, which were found in that order 5'----3' upstream of most yeast ribosomal protein genes, were present within this interval. We found that substitution of the CYC1-lacZ upstream activation site with the fragment from nucleotides -298 to -172 upstream of RP39A, containing the HOMOL1-RPG-T-rich motif in that 5'----3' orientation, fully restored expression of the CYC1-lacZ gene. The essentially of HOMOL1, the RPG sequence, and the T-rich region for wild-type levels of expression of RP39A, the conserved location and order of these sequence motifs in yeast ribosomal protein genes, and the ability of a DNA fragment carrying these three sequence elements to substitute for the upstream activation site regions of CYC1 indicate that these three oligonucleotides may be essential to the transcription of yeast ribosomal protein genes.


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