BRF1, a subunit of RNA polymerase III transcription factor TFIIIB, is essential for cell growth of Trypanosoma brucei.
RNA polymerase III (Pol III) synthesizes small RNA molecules that are essential for cell viability. Accurate initiation of transcription by Pol III requires general transcription factor TFIIIB, which is composed of three subunits: TFIIB-related factor BRF1, TATA-binding protein and BDP1. Here we report the molecular characterization of BRF1 in Trypanosoma brucei (TbBRF1), a parasitic protozoa that shows distinctive transcription characteristics. In silico analysis allowed the detection in TbBRF1 of the three conserved domains located in the N-terminal region of all BRF1 orthologues, namely a zinc ribbon motif and two cyclin repeats. Homology modelling suggested that, similarly to other BRF1 and TFIIB proteins, the TbBRF1 cyclin repeats show the characteristic structure of five α-helices per repeat, connected by a short random-coiled linker. As expected for a transcription factor, TbBRF1 was localized in the nucleus. Knock-down of TbBRF1 by RNA interference (RNAi) showed that this protein is essential for the viability of procyclic forms of T. brucei, since ablation of TbBRF1 led to growth arrest of the parasites. Nuclear run-on and quantitative real-time PCR analyses demonstrated that transcription of all the Pol III-dependent genes analysed was reduced, at different levels, after RNAi induction.
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
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Vélez-Ramírez
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
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Florencio-Martínez
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
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Romero-Meza
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
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Rojas-Sánchez
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
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Moreno-Campos
Departamento de Infectómica y Patogénesis Molecular,Centro de Investigación y de Estudios Avanzados del IPN,Av. IPN 2508,México,D.F.,CP 07360,México.
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Arroyo
Departamento de Biotecnología y Bioingeniería,Centro de Investigación y de Estudios Avanzados del IPN,Av. IPN 2508,México,D.F.,CP 07360,México.
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Ortega-López
Departamento de Biomedicina Molecular,Centro de Investigación y de Estudios Avanzados del IPN,Av. IPN 2508,México,D.F.,CP 07360,México.
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Manning-Cela
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
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Martínez-Calvillo
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D017124:Conserved Sequence; D016213:Cyclins / Q000737:chemistry; D055785:Gene Knockdown Techniques; D008297:Male; D012320:RNA Polymerase III / Q000235:genetics*; D011817:Rabbits; D016415:Sequence Alignment; D035381:TATA-Binding Protein Associated Factors / Q000737:chemistry / Q000502:physiology*; D035361:Transcription Factor TFIIIB / Q000502:physiology*; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000235:genetics / Q000254:growth & development*
D016213:Cyclins; D035381:TATA-Binding Protein Associated Factors; D035361:Transcription Factor TFIIIB; D012320:RNA Polymerase III
BRF1; Pol III transcription; Trypanosoma brucei; gene expression