IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
RIBOSOME INACTIVATING PROTEINS FOR STUDYING Trypanosoma cruzi RIBOSOMES
Autor/es:
JURI AYUB MAXIMILIANO; SMULSKI CR; MA KW; GÓMEZ K; REYES L; LEVIN MJ; ARAÚJO AP; WONG KB; ALGRANATI ID
Lugar:
Recife, Brasil
Reunión:
Congreso; XVI World Congress of the Internacional Society on Toxinology; 2009
Resumen:
Trypanosoma cruzi is an ancient eukaryotic parasite causing Chagas Disease, an endemic disease in Latin America. Several evidences suggest that T. cruzi ribosomes have remarkable differences with their mammalian counterpart. Ribosome Inactivating Proteins (RIPs) inhibit protein synthesis by depurinating a conserved adenine residue in the Sarcin Ricin Loop (SRL). Different RIPs have variable activity on ribosomes from different organims (i.e. prokaryotes and eukaryotes). We evaluated the activity of four RIPs: Trichosanthin (TCS), Pokewed Antiviral Protein (PAP), pulchellin and ME1 from Mirabilis expansa, on ribosomes from Rattus rattus, Trypanosoma cruzi and E. coli. Interestingly, T. cruzi ribosomes were markedly resistant to TCS comparing to mammalian particles (IC50 value was ~1,000 fold higher). In spite of this, at high doses TCS specifically depurinated the T. cruzi SRL, as detected by aniline treatment. This lower activity against parasite ribosomes was due, at least partially, to a lower (15 fold decrease) ribosome-toxin association rate, as determined by Surface Plasmon Resonance (SPR). TCS has been shown to interact with the C-terminal end of mammalian ribosomal P proteins. Similar observations have been made recently with other two RIPs; Ricin and Shiga-like toxin 1. By using a recombinant antibody, we show that TCS and pulchellin interact with the C-terminal peptide of P proteins on T. cruzi ribosomes, and this interaction is needed for full activity of toxins. However, TCS residues interacting with P proteins are not conserved in pulchellin, suggesting that the ability to interact with P proteins might have evolved independently in different RIPs. On the other hand, blocking of P proteins peptide had no effect on the activity of ME1 and PAP. We propose that testing different RIPs against T. cruzi ribosomes would reveal important parasite-specific ribosomal features. Moreover, these approaches would also help to improve our understanding the molecular mechanisms differences among RIPs.