Intein Prp8: potencial terapêutico de um elemento genético invasivo

Abstract

Inteins are genetic mobile elements that occur inserted within protein-coding genes, which are, usually, housekeeping genes. They are transcribed and translated along with the host gene, then catalyze their own splicing from its host protein, re-establishing their functional conformation. We developed an experimenal model to evaluate the splicing of Prp8 intein from the yeast pathogen Cryptococcus neoformans (CnePrp8i) in Saccharomyces cerevisiae Ura3 protein-coding gene as the non-native protein host for CnePrp8i. Since Prp8 inteins are found in several important fungal pathogens, causing from cutaneous to systemic mycosis, and are absent in mammals, they are considered potential therapeutic targets, because once their splicing is inhibited, the host protein would be no longer functional. Two different CnePrp8i-containing constructions were created and tested, although in only one of them the intein splicing was possible, as well as the full functionality of the host protein, the Ura3. In order to rule out any possible RNA splicing the presence of CnePrp8i at the mRNA level was confirmed by RT-PCR and the Ura3 expression was confirmed by cell grown on appropriate media (SC –His –Ura and 5-FoA media), as well as by western-blot. Cisplatin has been described as a RecA intein splicing inhibitor in Mycobacterium tuberculosis and therefore was tested as a possible validator, but it showed a low inhibition in our system. By using this heterologous system, new potential protein splicing inhibitors may be discovered and used in the future as a new class of drugs for mycosis treatment.