RESUMO
BACKGROUND: RNA-binding proteins (RBPs) are well known as key factors in gene expression regulation in eukaryotes. These proteins associate with mRNAs and other proteins to form mRNP complexes that ultimately determine the fate of target transcripts in the cell. This association is usually mediated by an RNA-recognition motif (RRM). In the case of trypanosomatids, these proteins play a paramount role, as gene expression regulation is mostly posttranscriptional. Despite their relevance in the life cycle of Trypanosoma cruzi, the causative agent of Chagas' disease, to date, few RBPs have been characterized in this parasite. RESULTS: We investigated the role of DRBD2 in T. cruzi, an RBP with two RRM domains that is associated with cytoplasmic translational complexes. We show that DRBD2 is an ortholog of the Gbp2 in yeast, an SR-rich protein involved in mRNA quality control and export. We used an immunoprecipitation assay followed by shotgun proteomics and RNA-seq to assess the interaction partners of the DRBD2-mRNP complex in epimastigotes. The analysis identified mostly proteins involved in RNA metabolism and regulation, such as ALBA1, ALBA3, ALBA4, UBP1, UBP2, DRBD3, and PABP2. The RNA-seq results showed that most of the transcripts regulated by the DRBD2 complex mapped to hypothetical proteins related to multiple processes, such as to biosynthetic process, DNA metabolic process, protein modification, and response to stress. CONCLUSIONS: The identification of regulatory proteins in the DRBD2-mRNP complex corroborates the important role of DRBD2 in gene expression regulation in T. cruzi. We consider these results an important contribution to future studies regarding gene expression regulation in T. cruzi, especially in the field of RNA-binding proteins.
Assuntos
Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/genética , Ribonucleoproteínas/metabolismo , Trypanosoma cruzi/metabolismo , Regulação da Expressão Gênica , Ligação Proteica , Domínios Proteicos , Proteômica , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Proteínas de Ligação a RNA/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Análise de Sequência de RNA , Homologia de Sequência de Aminoácidos , Trypanosoma cruzi/genéticaRESUMO
Real-time polymerase chain reaction (qPCR) using 16S rDNA is an alternative to conventional culture-based tests. The aim of this study was to compare the conventional culture method with qPCR using 16S rDNA in a model of cardiac tissue contamination. Samples of cardiac tissue for artificial contamination with Escherichia coli and control samples were submitted for DNA extraction, which was conducted by selective and alkaline lysis and purification steps. A standard curve for 16S rDNA was constructed to determine the efficiency and analytical sensitivity of the assay in concentrations from 106 to 102 c.f.u. ml-1 using TaqMan Master Mix. 16S rDNA was detected in all contaminated samples; however, it was not detected in the the final washing step solution of the sample with a bioburden of 102 c.f.u. ml-1. Using qPCR is a potential alternative to conventional culture for microbiological safety testing of allograft tissues for biobanking, reducing the time and labour input required.
