The complete structure of VIPER, an unsual LTR retroelement present in Trypanosomes but not in Leishmania major

LEVIN, MARIANO J.; LORENZI, HERNAN A.; DOS SANTOS FERREIRA, VERONICA; ROBLEDO, GERMÁN

Congreso; XL Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2004

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB).

VIPER was initially characterized as a 2,359 bp long retroelement of Trypanosoma cruzi associated with SIRE (Short Interspersed Repetitive Element). Sequence comparisons of its RT-RNase H domains determine its classification in the family of LTR. Analysis of different CL-Brener genomic sequences allowed the identification of a 4,480 bp long VIPER that includes an ORF for gag protein, next to it an ORF encoding for tyrosine recombinase and the previously mentioned RT-RNase H ORF. This structure is unusual for a LTR retrotransposon because it lacks the long terminal repeats that are replaced at the 5? end by the first 182 bp of SIRE and at the 3? end by the SIRE?s last 226 bp. Using BLAST we were able to identify VIPER-like retroelements in Trypanosoma brucei, but not in Leishmania major. Further analysis demonstrated that in T. brucei VIPER is found within 5? and 3? sequences that bare homology with SIRE. Genome wide analysis of the recently sequenced trypanosomatid genomes strongly suggest that extinction and expansions of LTR and non LTR retroelement families correlate with parasite speciation.