Role of Trypanosoma cruzi Polypirimidine tract binding protein in dicistronic pre-mRNA processing

CAMPO, V; DE GAUDENZI, JG; IZCOVICH, R; COLLAERT, V; FRASCH, AC

Mendoza

Congreso; XLVIII Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2012

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Trypanosome gene expression clusters are co-transcribed by RNAPII to yield polycistronic pre-mRNAs. During mRNA maturation, polycistrons are processed into monocistrons by two coupled reactions, trans-splicing at the 5´ and polyadenylation at the 3´ end. We have previously observed that alternative trans-splicing can produce dicistronic pre-RNA molecules or transcripts with long 3´untranslated regions. These pre-RNAs should be processed by a post-transcriptional trans-splicing event to produce mature mRNAs. Our hypothesis is that trans-splicing is a regulated process serving as another mechanism for gene expression regulation. We focus in the identification of pre-RNA molecules and the analysis of trans-splicing regulation factors. In this context, we have previously described a dicistronic unit containing coding sequences for two U-rich RNA binding proteins. Now, we found that dicistronic RNAs from parasites transfected with fusion tagged recombinant constructs are not translated into protein products. Furthermore, DRBD4, a trypanosome homologue of the PTB splicing regulator, is involved in the dicistronic processing. Finally, sequence analysis of a cDNA library obtained from coimmunoprecipitated DRBD4-associated RNAs allowed for the identification of 24 target transcripts, including 15 new putative dicistronic units, most of them coding for hypothetical and RNA-binding proteins.