title: ABCG-like transporter of Trypanosoma cruzi involved in benznidazole resistance: gene polymorphisms disclose inter-strain intragenic recombination in hybrid isolates.
abstract: Benznidazole (BZ) is one of the two drugs for Chagas disease treatment. In a previous study we showed that the Trypanosoma cruzi ABCG-like transporter gene, named TcABCG1, is over-expressed in parasite strains naturally resistant to BZ and that the gene of TcI BZ-resistant strains exhibited several single nucleotide polymorphisms (SNPs) as compared to the gene of CL Brener BZ-susceptible strain. Here we report the sequence of TcABCG1 gene of fourteen T. cruzi strains, with diverse degrees of BZ sensitivity and belonging to different discrete typing units (DTUs) and Tcbat group. Although DTU-specific SNPs and amino acid changes were identified, no direct correlation with BZ-resistance phenotype was found. Thus, it is plausible that the transporter abundance is a determinant factor for drug resistance, as pointed out above. Sequence data were used for Bayesian phylogenies and network genealogy analysis. The network showed a high degree of reticulation suggesting genetic exchange between the parasites. TcI and TcII clades were clearly separated. Tcbat sequences were close to TcI. A fourth clade clustered TcABCG1 haplotypes of TcV, TcVI and TcIII strains, with closer proximity to TcI. Analysis of the recombination patterns indicated that hybrid strains contain haplotypes that are mosaics most likely derived by intragenic recombination of parental sequences. The data confirm that TcII and TcIII as the parentals of TcV and TcVI DTUs. Since genetic fingerprint of TcI was found in TcIII, we sustain the previously proposed "Two Hybridization model" for the origin of hybrid strains. Among the twenty best BLASTP hits in databases, orthologues of TcABCG1 transporter were found in Leishmania spp. and African trypanosomes, though their function remains undescribed.
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
authors: Jaques
authors: J
authors: Franco
authors: Laboratório de Genômica Evolutiva e Biocomplexidade, Universidade Federal de São Paulo, Rua Pedro de Toledo 669, 04039-032 São Paulo, SP, Brazil.
authors: Renata C
authors: RC
authors: Ferreira
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
authors: Susan
authors: S
authors: Ienne
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil. Electronic address: zingales@iq.usp.br.
authors: Bianca
authors: B
authors: Zingales
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004351:Drug Resistance; D017125:Genes, Protozoan; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009593:Nitroimidazoles / Q000494:pharmacology*; D021261:Parasitic Sensitivity Tests; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D014344:Trypanocidal Agents / Q000494:pharmacology*; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000235:genetics*
chemical_list: D018528:ATP-Binding Cassette Transporters; D009593:Nitroimidazoles; D014344:Trypanocidal Agents; C009999:benzonidazole
keywords: ATP-binding cassette transporter; Benznidazole sensitivity; Intragenic recombination; Network genealogy; Orthologues in trypanosomatids; Trypanosoma cruzi DTUs