Taenia solium TAF6 and TAF9 binds to a putative Downstream Promoter Element present in TsTBP1 gene core promoter

Abstract

We have cloned and characterized the gene encoding to Taenia solium TATA binding protein 1 (TsTBP1). It spans 1481 bp and its coding region is interrupted by four introns that possess the consensus donor/acceptor sequences. It produces a protein of 238 amino acids residues, which presented all the classical motives of the TBP1. On the core promoter region we identified putative binding sites for NF1, AP-1, YY1, TAF1/TAF2 and TAF6/TAF9, and the TSS that corresponds to an A+1. Southern and Northern blot analysis showed that TsTBP1 is encoded by a single gene, which produce a messenger of about 1.1 kbp with a higher differential expression in adult than the larval stage. Moreover, two putative TATA boxes were identified at -97 and -69 bp (relative to the TSS), likewise a Downstream Promoter Element (DPE) was located at +27 to +31 bp. EMSA experiments did not show any component of cysticerci nuclear extracts bound to the putative TATA-box elements; in contrast TAF6 and TAF9 bind to the DPE, showing that TsTBP1 is a TATA-less gen. On the other hand, TAF6 and TAF9 were localized on the nucleus from cells of T. crassiceps cysticerci bladder walls. By using the amino acid sequences of T. solium TAF6 (TsTAF6) and TAF9 (TsTAF9), we constructed a molecular model showing interaction between DPE-TsTAF6 and TsTAF6-TsTAF9. Finally, an in silico analysis of the core promoters of Taeniidae family genes showed that TATA-box and DPE are homologous to the mammalian elements, but not so the Inr. The low identity between TAF9 from cestodes and mammals open the possibility to use it as target to interrupt or modulate the transcription of TATA-box less genes in cestodes as a novel therapeutic strategy.\n\nAuthor summaryNeurocysticercosis still being a health problem in developing countries. Mexico reports a prevalence of 2.5% in the total patients from National Institute of Neurology and Neurosurgery. Several efforts have been made in different fields to study Taenia solium, and although the Genome Project has been published and released the genomic sequence of this parasite; the transcriptional mechanisms this organism remains unexplored. We isolated and characterized Taenia solium TATA-Binding Protein 1 (TsTBP1) gene and TBP-associated factor 6 and 9 cDNAs (TsTAF6 and TsTAF9, respectively). Our principal findings are: 1.- Identification of cis and trans elements in the core promoter of TsTBP1 gene. 2.- The TsTBP1 gene is a TATA-less promoter. 3.- Cloning of cDNAs to TsTAF6 and TsTAF9, 4.- Identification of a DPE in the core promoter of TsTBP1 gene, which interacts with TAF6 and TAF9, 5.- Construction of a molecular model that shows the interaction between DPE, TAF6, and TAF9; and 6.- A proposal of consensus sequences for TATA-box, Inr and DPE presented on Taeniidae family core promoters.