Cloning and characterization of SRP1, a suppressor of temperature-sensitive RNA polymerase I mutations, in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (12) ◽  
pp. 5640-5651
Author(s):  
R Yano ◽  
M Oakes ◽  
M Yamaghishi ◽  
J A Dodd ◽  
M Nomura

The SRP1-1 mutation is an allele-specific dominant suppressor of temperature-sensitive mutations in the zinc-binding domain of the A190 subunit of Saccharomyces cerevisiae RNA polymerase I (Pol I). We found that it also suppresses temperature-sensitive mutations in the zinc-binding domain of the Pol I A135 subunit. This domain had been suggested to be in physical proximity to the A190 zinc-binding domain. We have cloned the SRP1 gene and determined its nucleotide sequence. The gene encodes a protein of 542 amino acids consisting of three domains: the central domain, which is composed of eight (degenerate) 42-amino-acid contiguous tandem repeats, and the surrounding N-terminal and C-terminal domains, both of which contain clusters of acidic and basic amino acids and are very hydrophilic. The mutational alteration (P219Q) responsible for the suppression was found to be in the central domain. Using antibody against the SRP1 protein, we have found that SRP1 is mainly localized at the periphery of the nucleus, apparently more concentrated in certain regions, as suggested by a punctate pattern in immunofluorescence microscopy. We suggest that SRP1 is a component of a larger macromolecular complex associated with the nuclear envelope and interacts with Pol I either directly or indirectly through other components in the structure containing SRP1.

1992 ◽  
Vol 12 (12) ◽  
pp. 5640-5651 ◽  
Author(s):  
R Yano ◽  
M Oakes ◽  
M Yamaghishi ◽  
J A Dodd ◽  
M Nomura

The SRP1-1 mutation is an allele-specific dominant suppressor of temperature-sensitive mutations in the zinc-binding domain of the A190 subunit of Saccharomyces cerevisiae RNA polymerase I (Pol I). We found that it also suppresses temperature-sensitive mutations in the zinc-binding domain of the Pol I A135 subunit. This domain had been suggested to be in physical proximity to the A190 zinc-binding domain. We have cloned the SRP1 gene and determined its nucleotide sequence. The gene encodes a protein of 542 amino acids consisting of three domains: the central domain, which is composed of eight (degenerate) 42-amino-acid contiguous tandem repeats, and the surrounding N-terminal and C-terminal domains, both of which contain clusters of acidic and basic amino acids and are very hydrophilic. The mutational alteration (P219Q) responsible for the suppression was found to be in the central domain. Using antibody against the SRP1 protein, we have found that SRP1 is mainly localized at the periphery of the nucleus, apparently more concentrated in certain regions, as suggested by a punctate pattern in immunofluorescence microscopy. We suggest that SRP1 is a component of a larger macromolecular complex associated with the nuclear envelope and interacts with Pol I either directly or indirectly through other components in the structure containing SRP1.


1991 ◽  
Vol 11 (2) ◽  
pp. 754-764 ◽  
Author(s):  
R Yano ◽  
M Nomura

The SRP3-1 mutation is an allele-specific suppressor of temperature-sensitive mutations in the largest subunit (A190) of RNA polymerase I from Saccharomyces cerevisiae. Two mutations known to be suppressed by SRP3-1 are in the putative zinc-binding domain of A190. We have cloned the SRP3 gene by using its suppressor activity and determined its complete nucleotide sequence. We conclude from the following evidence that the SRP3 gene encodes the second-largest subunit (A135) of RNA polymerase I. First, the deduced amino acid sequence of the gene product contains several regions with high homology to the corresponding regions of the second-largest subunits of RNA polymerases of various origins, including those of RNA polymerase II and III from S. cerevisiae. Second, the deduced amino acid sequence contains known amino acid sequences of two tryptic peptides from the A135 subunit of RNA polymerase I purified from S. cerevisiae. Finally, a strain was constructed in which transcription of the SRP3 gene was controlled by the inducible GAL7 promoter. When this strain, which can grow on galactose but not on glucose, was shifted from galactose medium to glucose medium, a large decrease in the cellular concentration of A135 was observed by Western blot analysis. We have also identified the specific amino acid alteration responsible for suppression by SRP3-1 and found that it is located within the putative zinc-binding domain conserved among the second-largest subunits of eucaryotic RNA polymerases. From these results, it is suggested that this putative zinc-binding domain is in physical proximity to and interacts with the putative zinc-binding domain of the A190 subunit.


1991 ◽  
Vol 11 (2) ◽  
pp. 746-753 ◽  
Author(s):  
J H McCusker ◽  
M Yamagishi ◽  
J M Kolb ◽  
M Nomura

Starting with two temperature-sensitive mutants (rpa190-1 and rpa190-5) of Saccharomyces cerevisiae, both of which are amino acid substitutions in the putative zinc-binding domain of the largest subunit (A190) of RNA polymerase I, we have isolated many independent pseudorevertants carrying extragenic suppressors (SRP) of rpa190 mutations. All the SRP mutations were dominant over the corresponding wild-type genes. They were classified into at least seven different loci by crossing each suppressed mutant with all of the other suppressed mutants and analyzing segregants. SRP mutations representing each of the seven loci were studied for their effects on other known rpa190 mutations. All of the SRP mutations were able to suppress both rpa190-1 and rpa190-5. In addition, one particular suppressor, SRP5, was found to suppress two other rpa190 mutations as well as an rpa190 deletion. Southern blot analysis combined with genetic crosses demonstrated that SRP5 maps to a region on chromosome XV loosely linked to rpa190 and represents a transposed mutant gene in two copies. Analysis of the A190 subunit by using anti-A190 antiserum indicated that the cellular concentration of A190 and hence of RNA polymerase I decreases in rpa190-1 mutants after a shift to 37 degrees C and that in the mutant strain carrying SRP5 this decrease is partially alleviated, presumably because of increased synthesis caused by increased gene dosage. These results suggest that the zinc-binding domain plays an important role in protein-protein interaction essential for the assembly and/or stability of the enzyme, regardless of whether it also participates directly in the interaction of the assembled enzyme with DNA.


1991 ◽  
Vol 11 (2) ◽  
pp. 746-753 ◽  
Author(s):  
J H McCusker ◽  
M Yamagishi ◽  
J M Kolb ◽  
M Nomura

Starting with two temperature-sensitive mutants (rpa190-1 and rpa190-5) of Saccharomyces cerevisiae, both of which are amino acid substitutions in the putative zinc-binding domain of the largest subunit (A190) of RNA polymerase I, we have isolated many independent pseudorevertants carrying extragenic suppressors (SRP) of rpa190 mutations. All the SRP mutations were dominant over the corresponding wild-type genes. They were classified into at least seven different loci by crossing each suppressed mutant with all of the other suppressed mutants and analyzing segregants. SRP mutations representing each of the seven loci were studied for their effects on other known rpa190 mutations. All of the SRP mutations were able to suppress both rpa190-1 and rpa190-5. In addition, one particular suppressor, SRP5, was found to suppress two other rpa190 mutations as well as an rpa190 deletion. Southern blot analysis combined with genetic crosses demonstrated that SRP5 maps to a region on chromosome XV loosely linked to rpa190 and represents a transposed mutant gene in two copies. Analysis of the A190 subunit by using anti-A190 antiserum indicated that the cellular concentration of A190 and hence of RNA polymerase I decreases in rpa190-1 mutants after a shift to 37 degrees C and that in the mutant strain carrying SRP5 this decrease is partially alleviated, presumably because of increased synthesis caused by increased gene dosage. These results suggest that the zinc-binding domain plays an important role in protein-protein interaction essential for the assembly and/or stability of the enzyme, regardless of whether it also participates directly in the interaction of the assembled enzyme with DNA.


1991 ◽  
Vol 11 (2) ◽  
pp. 754-764
Author(s):  
R Yano ◽  
M Nomura

The SRP3-1 mutation is an allele-specific suppressor of temperature-sensitive mutations in the largest subunit (A190) of RNA polymerase I from Saccharomyces cerevisiae. Two mutations known to be suppressed by SRP3-1 are in the putative zinc-binding domain of A190. We have cloned the SRP3 gene by using its suppressor activity and determined its complete nucleotide sequence. We conclude from the following evidence that the SRP3 gene encodes the second-largest subunit (A135) of RNA polymerase I. First, the deduced amino acid sequence of the gene product contains several regions with high homology to the corresponding regions of the second-largest subunits of RNA polymerases of various origins, including those of RNA polymerase II and III from S. cerevisiae. Second, the deduced amino acid sequence contains known amino acid sequences of two tryptic peptides from the A135 subunit of RNA polymerase I purified from S. cerevisiae. Finally, a strain was constructed in which transcription of the SRP3 gene was controlled by the inducible GAL7 promoter. When this strain, which can grow on galactose but not on glucose, was shifted from galactose medium to glucose medium, a large decrease in the cellular concentration of A135 was observed by Western blot analysis. We have also identified the specific amino acid alteration responsible for suppression by SRP3-1 and found that it is located within the putative zinc-binding domain conserved among the second-largest subunits of eucaryotic RNA polymerases. From these results, it is suggested that this putative zinc-binding domain is in physical proximity to and interacts with the putative zinc-binding domain of the A190 subunit.


1993 ◽  
Vol 13 (1) ◽  
pp. 114-122 ◽  
Author(s):  
Y Nogi ◽  
R Yano ◽  
J Dodd ◽  
C Carles ◽  
M Nomura

We have previously isolated mutants of Saccharomyces cerevisiae that are primarily defective in transcription of 35S rRNA genes by RNA polymerase I and have identified genes (RRN1 to RRN9) involved in this process. We have now cloned the RRN4 gene by complementation of the temperature-sensitive phenotype of the rrn4-1 mutant and have determined its complete nucleotide sequence. The following results demonstrate that the RRN4 gene encodes the A12.2 subunit of RNA polymerase I. First, RRN4 protein expressed in Escherichia coli reacted with a specific antiserum against A12.2. Second, amino acid sequences of three tryptic peptides obtained from A12.2 were determined, and these sequences are found in the deduced amino acid sequence of the RRN4 protein. The amino acid sequence of the RRN4 protein (A12.2) is similar to that of the RPB9 (B12.6) subunit of yeast RNA polymerase II; the similarity includes the presence of two putative zinc-binding domains. Thus, A12.2 is a homolog of B12.6. We propose to rename the RRN4 gene RPA12. Deletion of RPA12 produces cells that are heat but not cold sensitive for growth. We have found that in such null mutants growing at permissive temperatures, the cellular concentration of A190, the largest subunit of RNA polymerase I, is lower than in the wild type. In addition, the temperature-sensitive phenotype of the rpa12 null mutants can be partially suppressed by RPA190 (the gene for A190) on multicopy plasmids. These results suggest that A12.2 plays a role in the assembly of A190 into a stable polymerase I structure.


1998 ◽  
Vol 18 (2) ◽  
pp. 665-675 ◽  
Author(s):  
Hsiu-Jung Lo ◽  
Han-Kuei Huang ◽  
Thomas F. Donahue

ABSTRACT The HIS4 gene in Saccharomyces cerevisiaewas put under the transcriptional control of RNA polymerase I to determine the in vivo consequences on mRNA processing and gene expression. This gene, referred to as rhis4, was substituted for the normal HIS4 gene on chromosome III. Therhis4 gene transcribes two mRNAs, of which each initiates at the polymerase (pol) I transcription initiation site. One transcript, rhis4s, is similar in size to the wild-typeHIS4 mRNA. Its 3′ end maps to the HIS4 3′ noncoding region, and it is polyadenylated. The second transcript,rhis4l, is bicistronic. It encodes the HIS4coding region and a second open reading frame, YCL184, that is located downstream of the HIS4 gene and is predicted to be transcribed in the same direction as HIS4 on chromosome III. The 3′ end of rhis4l maps to the predicted 3′ end of the YCL184 gene and is also polyadenylated. Based on in vivo labeling experiments, the rhis4 gene appears to be more actively transcribed than the wild-type HIS4 gene despite the near equivalence of the steady-state levels of mRNAs produced from each gene. This finding indicated that rhis4mRNAs are rapidly degraded, presumably due to the lack of a cap structure at the 5′ end of the mRNA. Consistent with this interpretation, a mutant form of XRN1, which encodes a 5′-3′ exonuclease, was identified as an extragenic suppressor that increases the half-life of rhis4 mRNA, leading to a 10-fold increase in steady-state mRNA levels compared to the wild-typeHIS4 mRNA level. This increase is dependent on pol I transcription. Immunoprecipitation by anticap antiserum suggests that the majority of rhis4 mRNA produced is capless. In addition, we quantitated the level of His4 protein in a rhis4 xrn1Δ genetic background. This analysis indicates that capless mRNA is translated at less than 10% of the level of translation of capped HIS4 mRNA. Our data indicate that polyadenylation of mRNA in yeast occurs despite HIS4 being transcribed by RNA polymerase I, and the 5′ cap confers stability to mRNA and affords the ability of mRNA to be translated efficiently in vivo.


2009 ◽  
Vol 9 (2) ◽  
pp. 325-335 ◽  
Author(s):  
Elisa Cesarini ◽  
Francesca Romana Mariotti ◽  
Francesco Cioci ◽  
Giorgio Camilloni

ABSTRACT In Saccharomyces cerevisiae the repeated units of the ribosomal locus, transcribed by RNA polymerase I (Pol I), are interrupted by nontranscribed spacers (NTSs). These NTS regions are transcribed by RNA polymerase III to synthesize 5S RNA and by RNA polymerase II (Pol II) to synthesize, at low levels, noncoding RNAs (ncRNAs). While transcription of both RNA polymerase I and III is highly characterized, at the ribosomal DNA (rDNA) locus only a few studies have been performed on Pol II, whose repression correlates with the SIR2-dependent silencing. The involvement of both chromatin organization and Pol I transcription has been proposed, and peculiar chromatin structures might justify “ribosomal” Pol II silencing. Reporter genes inserted within the rDNA units have been employed for these studies. We studied, in the natural context, yeast mutants differing in Pol I transcription in order to find whether correlations exist between Pol I transcription and Pol II ncRNA production. Here, we demonstrate that silencing at the rDNA locus represses ncRNAs with a strength inversely proportional to Pol I transcription. Moreover, localized regions of histone hyperacetylation appear in cryptic promoter elements when Pol II is active and in the coding region when Pol I is functional; in addition, DNA topoisomerase I site-specific activity follows RNA polymerase I transcription. The repression of ncRNAs at the rDNA locus, in response to RNA polymerase I transcription, could represent a physiological circuit control whose mechanism involves modification of histone acetylation.


2019 ◽  
Vol 295 (5) ◽  
pp. 1288-1299 ◽  
Author(s):  
Catherine E. Scull ◽  
Andrew M. Clarke ◽  
Aaron L. Lucius ◽  
David Alan Schneider

The sequence of the DNA template has long been thought to influence the rate of transcription by DNA-dependent RNA polymerases, but the influence of DNA sequence on transcription elongation properties of eukaryotic RNA polymerase I (Pol I) from Saccharomyces cerevisiae has not been defined. In this study, we observe changes in dinucleotide production, transcription elongation complex stability, and Pol I pausing in vitro in response to downstream DNA. In vitro studies demonstrate that AT-rich downstream DNA enhances pausing by Pol I and inhibits Pol I nucleolytic cleavage activity. Analysis of Pol I native elongating transcript sequencing data in Saccharomyces cerevisiae suggests that these downstream sequence elements influence Pol I in vivo. Native elongating transcript sequencing studies reveal that Pol I occupancy increases as downstream AT content increases and decreases as downstream GC content increases. Collectively, these data demonstrate that the downstream DNA sequence directly impacts the kinetics of transcription elongation prior to the sequence entering the active site of Pol I both in vivo and in vitro.


1993 ◽  
Vol 13 (1) ◽  
pp. 114-122
Author(s):  
Y Nogi ◽  
R Yano ◽  
J Dodd ◽  
C Carles ◽  
M Nomura

We have previously isolated mutants of Saccharomyces cerevisiae that are primarily defective in transcription of 35S rRNA genes by RNA polymerase I and have identified genes (RRN1 to RRN9) involved in this process. We have now cloned the RRN4 gene by complementation of the temperature-sensitive phenotype of the rrn4-1 mutant and have determined its complete nucleotide sequence. The following results demonstrate that the RRN4 gene encodes the A12.2 subunit of RNA polymerase I. First, RRN4 protein expressed in Escherichia coli reacted with a specific antiserum against A12.2. Second, amino acid sequences of three tryptic peptides obtained from A12.2 were determined, and these sequences are found in the deduced amino acid sequence of the RRN4 protein. The amino acid sequence of the RRN4 protein (A12.2) is similar to that of the RPB9 (B12.6) subunit of yeast RNA polymerase II; the similarity includes the presence of two putative zinc-binding domains. Thus, A12.2 is a homolog of B12.6. We propose to rename the RRN4 gene RPA12. Deletion of RPA12 produces cells that are heat but not cold sensitive for growth. We have found that in such null mutants growing at permissive temperatures, the cellular concentration of A190, the largest subunit of RNA polymerase I, is lower than in the wild type. In addition, the temperature-sensitive phenotype of the rpa12 null mutants can be partially suppressed by RPA190 (the gene for A190) on multicopy plasmids. These results suggest that A12.2 plays a role in the assembly of A190 into a stable polymerase I structure.


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