<scp>M</scp>af1 is a negative regulator of transcription in <scp><i>T</i></scp><i>rypanosoma brucei</i>

Romero-Meza, Gabriela; Vélez-Ramírez, Daniel E.; Florencio-Martínez, Luis E.; Román‐Carraro, Fiordaliso C.; Manning‐Cela, Rebeca; Hernández‐Rivas, Rosaura; Martínez‐Calvillo, Santiago

doi:10.1111/mmi.13568

Cited by 13 publications

(12 citation statements)

References 73 publications

(177 reference statements)

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“…The ChIP procedures were performed as previously described [31]. Briefly, 2 × 10 8 promastigotes were cross-linked with formaldehyde (final concentration of 1%) for 5 min at 37°C.…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, knockdown analysis by RNA interference demonstrated that Brf1 is indeed involved in Pol III transcription and that it is indispensable for cell survival of procyclic forms of T. brucei [30]. Another protein that participates in the regulation of Pol III transcription in T. brucei is Maf1, which inhibits tRNA and snRNA transcription by associating with their promoter regions [31].…”

Section: Introductionmentioning

confidence: 99%

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

Román‐Carraro

Florencio-Martínez

Romero-Meza

et al. 2019

BioMed Research International

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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.

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“…The ChIP procedures were performed as previously described [31]. Briefly, 2 × 10 8 promastigotes were cross-linked with formaldehyde (final concentration of 1%) for 5 min at 37°C.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Román‐Carraro

Florencio-Martínez

Romero-Meza

et al. 2019

BioMed Research International

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“…However, recently, several reports implicated various proteins in RNA Pol I and Pol III transcription regulation (Romero‐Meza et al. ; Stanne et al. ), while little is known about the factors involved in transcriptional regulation of Pol II‐driven genes.…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, it has been recently shown that TbMAF1, a negative regulator of RNA Pol III transcription, also downregulates transcription of SL‐RNA genes (Romero‐Meza et al. ). Thus, it seems that multiple negative regulators participate in the transcriptional control of this important molecule in trypanosomes.…”

Section: Discussionmentioning

confidence: 99%

The Trypanosoma brucei RNA‐Binding Protein TbRRM1 is Involved in the Transcription of a Subset of RNA Pol II‐Dependent Genes

Bañuelos

Levy

Níttolo

et al. 2019

J Eukaryotic Microbiology

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It has been long thought that RNA Polymerase (Pol) II transcriptional regulation does not operate in trypanosomes. However, recent reports have suggested that these organisms could regulate RNA Pol II transcription by epigenetic mechanisms. In this paper, we investigated the role of TbRRM1 in transcriptional regulation of RNA Pol II‐dependent genes by focusing both in genes located in a particular polycistronic transcription unit (PTU) and in the monocistronic units of the SL‐RNA genes. We showed that TbRRM1 is recruited throughout the PTU, with a higher presence on genes than intergenic regions. However, its depletion leads both to the decrease of nascent RNA and to chromatin compaction only of regions located distal to the main transcription start site. These findings suggest that TbRRM1 facilitates the RNA Pol II transcriptional elongation step by collaborating to maintain an open chromatin state in particular regions of the genome. Interestingly, the SL‐RNA genes do not recruit TbRRM1 and, after TbRRM1 knockdown, nascent SL‐RNAs accumulate while the chromatin state of these regions remains unchanged. Although it was previously suggested that TbRRM1 could regulate RNA Pol II‐driven genes, we provide here the first experimental evidence which involves TbRRM1 to transcriptional regulation.

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“…In addition, ablation of subunit Brf1 of TFIIIB in T. brucei reduced the expression of all Pol III-dependent genes analyzed, including 5S rRNA genes [102]. Interestingly, contrary to what occurs in other organisms, the downregulation or overexpression of the negative regulator Maf1 did not significantly change the levels of 5S rRNA in T. brucei [103].…”

Section: Ribosomal Rna Genesmentioning

confidence: 99%

Nucleolar Structure and Function in Trypanosomatid Protozoa

Martínez‐Calvillo

Florencio-Martínez

Nepomuceno‐Mejía

2019

Cells

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The nucleolus is the conspicuous nuclear body where ribosomal RNA genes are transcribed by RNA polymerase I, pre-ribosomal RNA is processed, and ribosomal subunits are assembled. Other important functions have been attributed to the nucleolus over the years. Here we review the current knowledge about the structure and function of the nucleolus in the trypanosomatid parasites Trypanosoma brucei, Trypanosoma cruzi and Leishmania ssp., which represent one of the earliest branching lineages among the eukaryotes. These protozoan parasites present a single nucleolus that is preserved throughout the closed nuclear division, and that seems to lack fibrillar centers. Trypanosomatids possess a relatively low number of rRNA genes, which encode rRNA molecules that contain large expansion segments, including several that are trypanosomatid-specific. Notably, the large subunit rRNA (28S-type) is fragmented into two large and four small rRNA species. Hence, compared to other organisms, the rRNA primary transcript requires additional processing steps in trypanosomatids. Accordingly, this group of parasites contains the highest number ever reported of snoRNAs that participate in rRNA processing. The number of modified rRNA nucleotides in trypanosomatids is also higher than in other organisms. Regarding the structure and biogenesis of the ribosomes, recent cryo-electron microscopy analyses have revealed several trypanosomatid-specific features that are discussed here. Additional functions of the nucleolus in trypanosomatids are also reviewed.

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Maf1 is a negative regulator of transcription in Trypanosoma brucei

Cited by 13 publications

References 73 publications

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

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

The Trypanosoma brucei RNA‐Binding Protein TbRRM1 is Involved in the Transcription of a Subset of RNA Pol II‐Dependent Genes

Nucleolar Structure and Function in Trypanosomatid Protozoa

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