DNA SEQUENCE DIVERSITY OF THE MINICIRCLE HYPERVARIABLE REGION OF TRYPANOSOMA CRUZI

NICOLÁS TOMASINI; FANNY RUSMAN; NOELIA FLORIDIA-YAPUR; PATRICIO DIOSQUE

Salta

Congreso; The LV Annual SAIB Meeting and XIV PABMB Congress; 2019

Sociedad Argentina de Bioquímica y Biología Molecular

Trypanosoma cruzi, the protozoan causative of Chagas disease, is classified into six main lineages: TcI-TcVI. This parasite, as all the kinetoplastids,has a unique and large mitochondrion that contains a complex network of DNA, the kinetoplast DNA (kDNA). The kDNA representsapproximately 20?25 % of the total cellular DNA in T. cruzi and consists of two kinds of circular DNA molecules: maxicircles and minicircles.Maxicircles contain mitochondrial genes characteristic of other eukaryotes. Minicircles are present in tens of thousands of copies. Each minicircleis organized into four highly conserved regions located 90° apart of each other, and an equal number of hypervariable regions (mHVRs)interspersed between the conserved regions. mHVRs code for short RNAs called guide RNAs (gRNAs). gRNAs are involved in the edition ofseveral mitochondrially encoded mRNAs. Until now, the genetic diversity of the mHVRs was virtually unknown. However, cross-hybridizationassays using mHVRs showed hybridization only between isolates belonging to the same lineage or even between genetic groups at the intra-lineagelevel. We developed an amplicon deep sequencing approach that allows an accurate knowledge of the sequence diversity of the hypervariableregion of kDNA minicircles in representative strains of the six main lineages of T. cruzi. This approach could be also used as a typing method forhundreds of samples at a time. Our results also allow the identification of the mHVR sequences coding for the gRNAs needed for the edition ofmitochondrially encoded mRNAs. The developed approach provides us also with the tools to further investigate other still unanswered questions,such as: What is the reason for strong variations in mHVR diversity among strains? How do hybrids deal with the biparental inheritance ofminicircles? what is the function, if any, of the mHVRs that do not code for gRNAs? How does the mHVRs repertoire evolve? Why is such anexpensive mRNA editing mechanism maintained?