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Castanon-Sanchez C.A.,Programa Institucional de Biomedicina Molecular | Luna-Arias J.P.,CINVESTAV | de Dios-Bravo Ma.G.,National Autonomous University of Mexico | Herrera-Aguirre M.E.,Valle Private University | And 3 more authors.
Protein Expression and Purification | Year: 2010

Entamoeba histolytica is the protozoan parasite which causes human amoebiasis. In this parasite, few encoding genes for transcription factors have been cloned and characterized. The E. histolytica TATA-box binding protein (EhTBP) is the first basal transcription factor that has been studied. To continue with the identification of other members of the basal transcription machinery, we performed an in silico analysis of the E. histolytica genome and found three loci encoding for polypeptides with similarity to EhTBP. One locus has a 100% identity to the previously Ehtbp gene reported by our group. The second locus encodes for a 212 aa polypeptide that is 100% identical to residues 23-234 from EhTBP. The third one encodes for a 216 aa polypeptide of 24 kDa that showed 42.6% identity and 73.7% similarity to EhTBP. This protein was named E. histolytica TBP-related factor 1 (EhTRF1). Ehtrf1 gene was expressed in bacteria and the purified 28 kDa recombinant polypeptide showed the capacity to bind to TATTTAAA-box by electrophoretic mobility shift assays. KD values for rEhTBP and rEhTRF1 were (1.71 ± 2.90) × 10-12 M and (1.12 ± 0.160) × 10-11 M, respectively. Homology modeling of EhTRF1 and EhTBP revealed that, although they were very similar, they showed some differences on their surfaces. Thus, E. histolytica is a unicellular organism having two members of the TBP family. © 2009 Elsevier Inc. All rights reserved. Source

Ortuno-Pineda C.,CINVESTAV | Galindo-Rosales J.M.,CINVESTAV | Calderon-Salinas J.V.,CINVESTAV | Villegas-Sepulveda N.,CINVESTAV | And 4 more authors.
PLoS ONE | Year: 2012

The splicing of the N exon in the pre-mRNA coding for the RE1-silencing transcription factor (REST) results in a truncated protein that modifies the expression pattern of some of its target genes. A weak 3'ss, three alternative 5'ss (N4-, N50-, and N62-5'ss) and a variety of putative target sites for splicing regulatory proteins are found around the N exon; two GGGG codes (G2-G3) and a poly-Uridine tract (N-PU) are found in front of the N50-5'ss. In this work we analyzed some of the regulatory factors and elements involved in the preferred selection of the N50-5'ss (N50 activation) in the small cell lung cancer cell line H69. Wild type and mutant N exon/β-globin minigenes recapitulated N50 exon splicing in H69 cells, and showed that the N-PU and the G2-G3 elements are required for N50 exon splicing. Biochemical and knockdown experiments identified these elements as U2AF65 and hnRNP H targets, respectively, and that they are also required for N50 exon activation. Compared to normal MRC5 cells, and in keeping with N50 exon activation, U2AF65, hnRNP H and other splicing factors were highly expressed in H69 cells. CLIP experiments revealed that hnRNP H RNA-binding occurs first and is a prerequisite for U2AF65 RNA binding, and EMSA and CLIP experiments suggest that U2AF65-RNA recognition displaces hnRNP H and helps to recruit other splicing factors (at least U1 70K) to the N50-5'ss. Our results evidenced novel hnRNP H and U2AF65 functions: respectively, U2AF65-recruiting to a 5'ss in humans and the hnRNP H-displacing function from two juxtaposed GGGG codes. © 2012 Ortuño-Pineda et al. Source

Pezet-Valdez M.,Programa Institucional de Biomedicina Molecular | Fernandez-Retana J.,Programa Institucional de Biomedicina Molecular | Da Ospina-Villa J.,Programa Institucional de Biomedicina Molecular | Ramirez-Moreno M.E.,Programa Institucional de Biomedicina Molecular | And 7 more authors.
PLoS ONE | Year: 2013

In eukaryotes, polyadenylation of pre-mRNA 3́ end is essential for mRNA export, stability and translation. Taking advantage of the knowledge of genomic sequences of Entamoeba histolytica, the protozoan responsible for human amoebiasis, we previously reported the putative polyadenylation machinery of this parasite. Here, we focused on the predicted protein that has the molecular features of the 25 kDa subunit of the Cleavage Factor Im (CFIm25) from other organisms, including the Nudix (nucleoside diphosphate linked to another moiety X) domain, as well as the RNA binding domain and the PAP/PAB interacting region. The recombinant EhCFIm25 protein (rEhCFIm25) was expressed in bacteria and used to generate specific antibodies in rabbit. Subcellular localization assays showed the presence of the endogenous protein in nuclear and cytoplasmic fractions. In RNA electrophoretic mobility shift assays, rEhCFIm25 was able to form specific RNA-protein complexes with the EhPgp5 mRNA 3́ UTR used as probe. In addition, Pull-Down and LC/ESI-MS/MS tandem mass spectrometry assays evidenced that the putative EhCFIm25 was able to interact with the poly(A) polymerase (EhPAP) that is responsible for the synthesis of the poly(A) tail in other eukaryotic cells. By Far-Western experiments, we confirmed the interaction between the putative EhCFIm25 and EhPAP in E. histolytica. Taken altogether, our results showed that the putative EhCFIm25 is a conserved RNA binding protein that interacts with the poly(A) polymerase, another member of the pre-mRNA 3́ end processing machinery in this protozoan parasite. © 2013 Pezet-Valdez et al. Source

Charcas-Lopez Md.el S.,Programa Institucional de Biomedicina Molecular | Garcia-Morales L.,Programa Institucional de Biomedicina Molecular | Pezet-Valdez M.,Programa Institucional de Biomedicina Molecular | Lopez-Camarillo C.,Valle de Mexico University | And 2 more authors.
Parasite (Paris, France) | Year: 2014

Entamoeba histolytica, the protozoan responsible for human amoebiasis, exhibits a great genome plasticity that is probably related to homologous recombination events. It contains the RAD52 epistasis group genes, including Ehrad51 and Ehrad54, and the Ehblm gene, which are key homologous recombination factors in other organisms. Ehrad51 and Ehrad54 genes are differentially transcribed in trophozoites when DNA double-strand breaks are induced by ultraviolet-C irradiation. Moreover, the EhRAD51 recombinase is overexpressed at 30 min in the nucleus. Here, we extend our analysis of the homologous recombination mechanism in E. histolytica by studying EhRAD51, EhRAD54, and EhBLM expression in response to DNA damage. Bioinformatic analyses show that EhRAD54 has the molecular features of homologous proteins, indicating that it may have similar functions. Western blot assays evidence the differential expression of EhRAD51, EhRAD54, and EhBLM at different times after DNA damage, suggesting their potential roles in the different steps of homologous recombination in this protozoan. © Ma. del Socorro Charcas-Lopez et al., published by EDP Sciences, 2014. Source

Rodriguez M.A.,CINVESTAV | Gomez C.,Programa Institucional de Biomedicina Molecular | Esther Ramirez M.,Programa Institucional de Biomedicina Molecular | Calixto-Galvez M.,CINVESTAV | Medel O.,Programa Institucional de Biomedicina Molecular
Journal of Biomedicine and Biotechnology | Year: 2010

Infections with protozoa parasites are associated with high burdens of morbidity and mortality across the developing world. Despite extensive efforts to control the transmission of these parasites, the spread of populations resistant to drugs and the lack of effective vaccines against them contribute to their persistence as major public health problems. Parasites should perform a strict control on the expression of genes involved in their pathogenicity, differentiation, immune evasion, or drug resistance, and the comprehension of the mechanisms implicated in that control could help to develop novel therapeutic strategies. However, until now these mechanisms are poorly understood in protozoa. Recent investigations into gene expression in protozoa parasites suggest that they possess many of the canonical machineries employed by higher eukaryotes for the control of gene expression at transcriptional, posttranscriptional, and epigenetic levels, but they also contain exclusive mechanisms. Here, we review the current understanding about the regulation of gene expression in Plasmodium sp., Trypanosomatids, Entamoeba histolytica and Trichomonas vaginalis. © 2010 Consuelo Gomez et al. Source

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