Functionally related transcripts have common RNA motifs for specific RNA-binding proteins in trypanosomes.
BACKGROUND
Trypanosomes mostly control gene expression by post-transcriptional events such as modulation of mRNA stability and translational efficiency. These mechanisms involve RNA-binding proteins (RBPs), which associate with transcripts to form messenger ribonucleoprotein (mRNP) complexes.


RESULTS
In this study, we report the identification of mRNA targets for Trypanosoma cruzi U-rich RBP 1 (TcUBP1) and T. cruzi RBP 3 (TcRBP3), two phylogenetically conserved proteins among Kinetoplastids. Co-immunoprecipitated RBP-associated RNAs were extracted from mRNP complexes and binding of RBPs to several targets was confirmed by independent experimental assays. Analysis of target transcript sequences allowed the identification of different signature RNA motifs for each protein. Cis-elements for RBP binding have a stem-loop structure of 30-35 bases and are more frequently represented in the 3'-untranslated region (UTR) of mRNAs. Insertion of the correctly folded RNA elements to a non-specific mRNA rendered it into a target transcript, whereas substitution of the RNA elements abolished RBP interaction. In addition, RBPs competed for RNA-binding sites in accordance with the distribution of different and overlapping motifs in the 3'-UTRs of common mRNAs.


CONCLUSIONS
Functionally related transcripts were preferentially associated with a given RBP; TcUBP1 targets were enriched in genes encoding proteins involved in metabolism, whereas ribosomal protein-encoding transcripts were the largest group within TcRBP3 targets. Together, these results suggest coordinated control of different mRNA subsets at the post-transcriptional level by specific RBPs.
Noé
Griselda
G
Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico Chascomús, UNSAM-CONICET, Av, Gral, Paz 5445, INTI, Edificio 24, 1650 San Martín, Provincia de Buenos Aires, Argentina. gri@iib.unsam.edu.ar
De Gaudenzi
Javier G
JG
Frasch
Alberto C
AC
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D030562:Databases, Protein; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D012313:RNA / Q000737:chemistry* / Q000145:classification; D016601:RNA-Binding Proteins / Q000737:chemistry*; D015203:Reproducibility of Results; D016415:Sequence Alignment; D014349:Trypanosoma cruzi / Q000235:genetics / Q000378:metabolism*
D016601:RNA-Binding Proteins; C500732:UBP1 protein, Trypanosoma cruzi; D012313:RNA