scholarly journals The Selenocysteine tRNA Gene in Leishmania major Is Transcribed by both RNA Polymerase II and RNA Polymerase III

2014 ◽  
Vol 14 (3) ◽  
pp. 216-227 ◽  
Author(s):  
Norma E. Padilla-Mejía ◽  
Luis E. Florencio-Martínez ◽  
Rodrigo Moreno-Campos ◽  
Juan C. Vizuet-de-Rueda ◽  
Ana M. Cevallos ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Leishmania Major ◽  
Single Gene ◽  
Rna Polymerase Iii ◽  
Transcriptional Analysis ◽  
Pol Ii ◽  
Content Type ◽  
Polymerase Iii ◽  
Pol Iii

ABSTRACT Eukaryotic tRNAs, transcribed by RNA polymerase III (Pol III), contain boxes A and B as internal promoter elements. One exception is the selenocysteine (Sec) tRNA (tRNA-Sec), whose transcription is directed by an internal box B and three extragenic sequences in vertebrates. Here we report on the transcriptional analysis of the tRNA-Sec gene in the protozoan parasite Leishmania major . This organism has unusual mechanisms of gene expression, including Pol II polycistronic transcription and maturation of mRNAs by trans splicing, a process that attaches a 39-nucleotide miniexon to the 5′ end of all the mRNAs. In L. major , tRNA-Sec is encoded by a single gene inserted into a Pol II polycistronic unit, in contrast to most tRNAs, which are clustered at the boundaries of polycistronic units. 5′ rapid amplification of cDNA ends and reverse transcription-PCR experiments showed that some tRNA-Sec transcripts contain the miniexon at the 5′ end and a poly(A) tail at the 3′ end, indicating that the tRNA-Sec gene is polycistronically transcribed by Pol II and processed by trans splicing and polyadenylation, as was recently reported for the tRNA-Sec genes in the related parasite Trypanosoma brucei . However, nuclear run-on assays with RNA polymerase inhibitors and with cells that were previously UV irradiated showed that the tRNA-Sec gene in L. major is also transcribed by Pol III. Thus, our results indicate that RNA polymerase specificity in Leishmania is not absolute in vivo , as has recently been found in other eukaryotes.

scholarly journals RNA polymerase III transcription in synthetic nuclei assembled in vitro from defined DNA templates.

1995 ◽  
Vol 15 (9) ◽  
pp. 4873-4883 ◽  
Author(s):  
K S Ullman ◽  
D J Forbes
Keyword(s):  
Rna Polymerase ◽  
Nuclear Structure ◽  
De Novo ◽  
Rna Polymerase Iii ◽  
Transcriptional Analysis ◽  
Dna Encoding ◽  
Nuclear Assembly ◽  
Polymerase Iii ◽  
Pol Iii

Although much is known of the basic control of transcription, little is understood of the way in which the structural organization of the nucleus affects transcription. Synthetic nuclei, assembled de novo in extracts of Xenopus eggs, would be predicted to have a large potential for approaching the role of nuclear structure in RNA biogenesis. Synthetic nuclei provide a system in which the genetic content of the nuclei, as well as the structural and enzymatic proteins within the nuclei, can be manipulated. In this study, we have begun to examine transcription in such nuclei by using the most simple of templates, RNA polymerase III (pol III)-transcribed genes. DNA encoding tRNA or 5S genes was added to an assembly extract, and nuclei were formed entirely from the pol III templates. Conditions which allowed nuclear assembly and pol III transcription to take place efficiently and simultaneously in the assembly extract were found. To examine whether pol III transcription could initiate within synthetic nuclei, or instead was inhibited in nuclei and initiated only on rare unincorporated templates, we identified transcriptional inhibitors that were excluded from nuclei. We found that these inhibitors, heparin and dextran sulfate, blocked pol III transcription in the absence of assembly but did not do so following nuclear assembly. At the concentrations used, the inhibitors had no deleterious effect on nuclear structure itself or on nuclear import. We conclude that pol III transcription is active in synthetic nuclei, and this conclusion is further strengthened by the finding that pol III transcripts could be coisolated with synthetic nuclei. The rapid and direct transcriptional analysis possible with pol III templates, coupled with the simple experimental criteria developed in this study for distinguishing between nuclear and non-nuclear transcription, should now allow a molecular analysis of the effect of nuclear structure on transcriptional and posttranscriptional control.

scholarly journals Engineered mini H1 promoters with dedicated RNA Polymerase II or III activity

2020 ◽  
pp. jbc.RA120.015386
Author(s):  
Zongliang Gao ◽  
Yme Ubeles van der Velden ◽  
Minghui Fan ◽  
Cynthia Alyssa van der Linden ◽  
Monique Vink ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Rna Polymerase Iii ◽  
Polymerase Activity ◽  
Attractive Alternative ◽  
Pol Ii ◽  
Guide Rnas ◽  
Non Coding Rna ◽  
Pol Iii ◽  
Short Hairpin Rnas

RNA polymerase III promoters such as 7SK, U6 and H1 are widely used for the expression of small non-coding RNAs, including short hairpin RNAs for RNAi experiments and guide RNAs for CRISPR-mediated genome editing. We previously reported dual RNA polymerase activity (Pol II/III) for the human H1 promoter and demonstrated that this promiscuous RNA polymerase use can be exploited for the simultaneous expression of both a non-coding RNA and an mRNA. However, this combination is not a desired feature in other experimental and therapeutic settings. To overcome this limitation of the H1 promoter we engineered a miniature H1/7SK hybrid promoter with minimal Pol II activity, thereby boosting the Pol III activity to a level that is higher than that of either parental promoter. In parallel, we also engineered small Pol II-specific H1 promoter variants and explored their use as general Pol II promoters for protein expression. The newly engineered promoter variants form an attractive alternative to the commonly-used H1 promoter in terms of activity and small promoter size, but also concerning safety by exclusive expression of the desired therapeutic transcript (either Pol II or Pol III, but not both).

scholarly journals Rbs1, a New Protein Implicated in RNA Polymerase III Biogenesis in Yeast Saccharomyces cerevisiae

2015 ◽  
Vol 35 (7) ◽  
pp. 1169-1181 ◽  
Author(s):  
Małgorzata Cieśla ◽  
Ewa Makała ◽  
Marta Płonka ◽  
Rafał Bazan ◽  
Kamil Gewartowski ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
De Novo ◽  
Rna Polymerase Iii ◽  
Growth Defect ◽  
Yeast Saccharomyces Cerevisiae ◽  
Content Type ◽  
Polymerase Iii ◽  
Cold Sensitive ◽  
Pol Iii ◽  
Synthetic Growth

Little is known about the RNA polymerase III (Pol III) complex assembly and its transport to the nucleus. We demonstrate that a missense cold-sensitive mutation,rpc128-1007, in the sequence encoding the C-terminal part of the second largest Pol III subunit, C128, affects the assembly and stability of the enzyme. The cellular levels and nuclear concentration of selected Pol III subunits were decreased inrpc128-1007cells, and the association between Pol III subunits as evaluated by coimmunoprecipitation was also reduced. To identify the proteins involved in Pol III assembly, we performed a genetic screen for suppressors of therpc128-1007mutation and selected the Rbs1 gene, whose overexpression enhancedde novotRNA transcription inrpc128-1007cells, which correlated with increased stability, nuclear concentration, and interaction of Pol III subunits. Therpc128-1007 rbs1Δ double mutant shows a synthetic growth defect, indicating thatrpc128-1007andrbs1Δ function in parallel ways to negatively regulate Pol III assembly. Rbs1 physically interacts with a subset of Pol III subunits, AC19, AC40, and ABC27/Rpb5. Additionally, Rbs1 interacts with the Crm1 exportin and shuttles between the cytoplasm and nucleus. We postulate that Rbs1 binds to the Pol III complex or subcomplex and facilitates its translocation to the nucleus.

scholarly journals Defective RNA Polymerase III is negatively regulated by the SUMO-Ubiquitin-Cdc48 Pathway

2018 ◽  
Author(s):  
Zheng Wang ◽  
Catherine Wu ◽  
Aaron Aslanian ◽  
John R. Yates ◽  
Tony Hunter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase ◽  
Neurodegenerative Disease ◽  
Regulatory Mechanism ◽  
Rna Polymerase Iii ◽  
Post Translational Modification ◽  
Pol Ii ◽  
Polymerase Iii ◽  
Defective Rna ◽  
Pol Iii

ABSTRACTTranscription by RNA polymerase III (Pol III) is an essential cellular process, and mutations in Pol III can cause neurodegenerative disease in humans. However, in contrast to Pol II transcription, which has been extensively studied, the knowledge of how Pol III is regulated is very limited. We report here that in budding yeast, Saccharomyces cerevisiae, Pol III is negatively regulated by the Small Ubiquitin-like MOdifier (SUMO), an essential post-translational modification pathway. Besides sumoylation, Pol III is also targeted by ubiquitylation and the Cdc48/p97 segregase, the three of which likely act in a sequential manner and eventually lead to proteasomal degradation of Pol III subunits, thereby repressing Pol III transcription. This study not only uncovered a regulatory mechanism for Pol III, but also suggests that the SUMO and ubiquitin modification pathways and the Cdc48/p97 segregase can be potential therapeutic targets for Pol III-related human diseases.

scholarly journals Structure-Function Analysis of the Human TFIIB-Related Factor II Protein Reveals an Essential Role for the C-Terminal Domain in RNA Polymerase III Transcription

2005 ◽  
Vol 25 (21) ◽  
pp. 9406-9418 ◽  
Author(s):  
Ashish Saxena ◽  
Beicong Ma ◽  
Laura Schramm ◽  
Nouria Hernandez
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Function Analysis ◽  
Rna Polymerase Iii ◽  
Related Factor ◽  
Pol Ii ◽  
Terminal Domain ◽  
U6 Promoter ◽  
Pol Iii ◽  
Type 3

ABSTRACT The transcription factors TFIIB, Brf1, and Brf2 share related N-terminal zinc ribbon and core domains. TFIIB bridges RNA polymerase II (Pol II) with the promoter-bound preinitiation complex, whereas Brf1 and Brf2 are involved, as part of activities also containing TBP and Bdp1 and referred to here as Brf1-TFIIIB and Brf2-TFIIIB, in the recruitment of Pol III. Brf1-TFIIIB recruits Pol III to type 1 and 2 promoters and Brf2-TFIIIB to type 3 promoters such as the human U6 promoter. Brf1 and Brf2 both have a C-terminal extension absent in TFIIB, but their C-terminal extensions are unrelated. In yeast Brf1, the C-terminal extension interacts with the TBP/TATA box complex and contributes to the recruitment of Bdp1. Here we have tested truncated Brf2, as well as Brf2/TFIIB chimeric proteins for U6 transcription and for assembly of U6 preinitiation complexes. Our results characterize functions of various human Brf2 domains and reveal that the C-terminal domain is required for efficient association of the protein with U6 promoter-bound TBP and SNAPc, a type 3 promoter-specific transcription factor, and for efficient recruitment of Bdp1. This in turn suggests that the C-terminal extensions in Brf1 and Brf2 are crucial to specific recruitment of Pol III over Pol II.

scholarly journals TFIIIB Subunit Bdp1 Participates in RNA Polymerase III Transcription in the Protozoan Parasite Leishmania major

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Fiordaliso C. Román-Carraro ◽  
Luis E. Florencio-Martínez ◽  
Gabriela Romero-Meza ◽  
Tomás Nepomuceno-Mejía ◽  
Julio C. Carrero ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Cell Line ◽  
Leishmania Major ◽  
Mutant Cell ◽  
Rna Polymerase Iii ◽  
Protozoan Parasite ◽  
5S Rrna ◽  
Mutant Cell Line ◽  
Polymerase Iii ◽  
Pol Iii

Leishmania major, a protozoan parasite that diverged early from the main eukaryotic lineage, exhibits unusual mechanisms of gene expression. Little is known in this organism about the transcription factors involved in the synthesis of tRNA, 5S rRNA, and snRNAs, transcribed by RNA Polymerase III (Pol III). Here we identify and characterize the TFIIIB subunit Bdp1 in L. major (LmBdp1). Bdp1 plays key roles in Pol III transcription initiation in other organisms, as it participates in Pol III recruitment and promoter opening. In silico analysis showed that LmBdp1 contains the typical extended SANT domain as well as other Bdp1 conserved regions. Nevertheless, LmBdp1 also displays distinctive features, including the presence of only one aromatic residue in the N-linker region. We were not able to produce null mutants of LmBdp1 by homologous recombination, as the obtained double replacement cell line contained an extra copy of LmBdp1, indicating that LmBdp1 is essential for the viability of L. major promastigotes. Notably, the mutant cell line showed reduced levels of the LmBdp1 protein, and its growth was significantly decreased in relation to wild-type cells. Nuclear run-on assays demonstrated that Pol III transcription was affected in the mutant cell line, and ChIP experiments showed that LmBdp1 binds to 5S rRNA, tRNA, and snRNA genes. Thus, our results indicate that LmBdp1 is an essential protein required for Pol III transcription in L. major.

scholarly journals RNA Polymerase III Transcripts and the PTB Protein Are Essential for the Integrity of the Perinucleolar Compartment

2003 ◽  
Vol 14 (6) ◽  
pp. 2425-2435 ◽  
Author(s):  
Chen Wang ◽  
Joan C. Politz ◽  
Thoru Pederson ◽  
Sui Huang
Keyword(s):  
Rna Polymerase ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Rna Polymerase Iii ◽  
Signal Recognition Particle ◽  
Pol Ii ◽  
Polymerase Iii ◽  
Perinucleolar Compartment ◽  
High Concentrations ◽  
Pol Iii

The perinucleolar compartment (PNC) is a nuclear substructure present in transformed cells. The PNC is defined by high concentrations of certain RNA binding proteins and a subset of small RNAs transcribed by RNA polymerase III (pol III), including the signal recognition particle RNA and an Alu RNA as reported here. To determine if the PNC is dependent on pol III transcription, HeLa cells were microinjected with the selective pol III inhibitor, Tagetin. This resulted in disassembly of the PNC, whereas inhibition of pol I by cycloheximide or pol II by α-amanitin did not significantly affect the PNC. However, overexpression of one of the PNC-associated RNAs from a pol II promoter followed by injection of Tagetin blocked the Tagetin-induced PNC disassembly, demonstrating that it is the RNA rather than pol III activity that is important for the PNC integrity. To elucidate the role of the PNC-associated protein PTB, its synthesis was inhibited by siRNA. This resulted in a reduction of the number of PNC-containing cells and the PNC size. Together, these findings suggest, as a working model, that PNCs may be involved in the metabolism of specific pol III transcripts in the transformed state and that PTB is one of the key elements mediating this process.

scholarly journals RNA Polymerase III, Ageing and Longevity

2021 ◽  
Vol 12 ◽  
Author(s):  
Yavuz Kulaberoglu ◽  
Yasir Malik ◽  
Gillian Borland ◽  
Colin Selman ◽  
Nazif Alic ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Fragile X ◽  
Rna Polymerase Iii ◽  
Model Organisms ◽  
Cellular Processes ◽  
Polymerase Iii ◽  
Age Related ◽  
Non Coding Rnas ◽  
Pol Iii

Transcription in eukaryotic cells is performed by three RNA polymerases. RNA polymerase I synthesises most rRNAs, whilst RNA polymerase II transcribes all mRNAs and many non-coding RNAs. The largest of the three polymerases is RNA polymerase III (Pol III) which transcribes a variety of short non-coding RNAs including tRNAs and the 5S rRNA, in addition to other small RNAs such as snRNAs, snoRNAs, SINEs, 7SL RNA, Y RNA, and U6 spilceosomal RNA. Pol III-mediated transcription is highly dynamic and regulated in response to changes in cell growth, cell proliferation and stress. Pol III-generated transcripts are involved in a wide variety of cellular processes, including translation, genome and transcriptome regulation and RNA processing, with Pol III dys-regulation implicated in diseases including leukodystrophy, Alzheimer’s, Fragile X-syndrome and various cancers. More recently, Pol III was identified as an evolutionarily conserved determinant of organismal lifespan acting downstream of mTORC1. Pol III inhibition extends lifespan in yeast, worms and flies, and in worms and flies acts from the intestine and intestinal stem cells respectively to achieve this. Intriguingly, Pol III activation achieved through impairment of its master repressor, Maf1, has also been shown to promote longevity in model organisms, including mice. In this review we introduce the Pol III transcription apparatus and review the current understanding of RNA Pol III’s role in ageing and lifespan in different model organisms. We then discuss the potential of Pol III as a therapeutic target to improve age-related health in humans.

scholarly journals BC1 RNA: transcriptional analysis of a neural cell-specific RNA polymerase III transcript.

1995 ◽  
Vol 15 (3) ◽  
pp. 1642-1650 ◽  
Author(s):  
J A Martignetti ◽  
J Brosius
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Iii ◽  
Neural Cell ◽  
Transcriptional Analysis ◽  
Upstream Region ◽  
Sequence Element ◽  
In Vitro System ◽  
Polymerase Iii ◽  
Pol Iii

Rodent BC1 RNA represents the first example of a neural cell-specific RNA polymerase III (Pol III) transcription product. By developing a rat brain in vitro system capable of supporting Pol III-directed transcription, we showed that the rat BC1 RNA intragenic promoter elements, comprising an A box element and a variant B box element, as well as its upstream region, containing octamer-binding consensus sequences and functional TATA and proximal sequence element sites, are necessary for transcription. The BC1 B box, lacking the invariant A residue found in the consensus B boxes of tRNAs, represents a functionally related and possibly distinct promoter element. The transcriptional activity of the BC1 B box element is greatly increased, in both a BC1 RNA and a chimeric tRNA(Leu) gene construct, when the BC1 5' flanking region is present and is appropriately spaced. Moreover, a tRNA consensus B-box sequence can efficiently replace the BC1 B box only if the BC1 upstream region is removed. These interactions, identified only in a homologous in vitro system, between upstream Pol II and intragenic Pol III promoters suggest a mechanism by which the tissue-specific BC1 RNA gene and possibly other Pol III-transcribed genes can be regulated.

scholarly journals Defective RNA polymerase III is negatively regulated by the SUMO-Ubiquitin-Cdc48 pathway

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Zheng Wang ◽  
Catherine Wu ◽  
Aaron Aslanian ◽  
John R Yates ◽  
Tony Hunter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase ◽  
Regulatory Mechanism ◽  
Rna Polymerase Iii ◽  
Post Translational Modification ◽  
Yeast Saccharomyces Cerevisiae ◽  
Pol Ii ◽  
Polymerase Iii ◽  
Defective Rna ◽  
Pol Iii

Transcription by RNA polymerase III (Pol III) is an essential cellular process, and mutations in Pol III can cause neurodegenerative disease in humans. However, in contrast to Pol II transcription, which has been extensively studied, the knowledge of how Pol III is regulated is very limited. We report here that in budding yeast, Saccharomyces cerevisiae, Pol III is negatively regulated by the Small Ubiquitin-like MOdifier (SUMO), an essential post-translational modification pathway. Besides sumoylation, Pol III is also targeted by ubiquitylation and the Cdc48/p97 segregase; these three processes likely act in a sequential manner and eventually lead to proteasomal degradation of Pol III subunits, thereby repressing Pol III transcription. This study not only uncovered a regulatory mechanism for Pol III, but also suggests that the SUMO and ubiquitin modification pathways and the Cdc48/p97 segregase can be potential therapeutic targets for Pol III-related human diseases.

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