title: The open reading frame 1 of the L1Tc retrotransposon of Trypanosoma cruzi codes for a protein with apurinic-apyrimidinic nuclease activity.
abstract: The deduced amino acid sequence of the open reading frame 1 (ORF1) of the L1Tc non-site-specific non-long terminal repeat retrotransposon of Trypanosoma cruzi exhibits a significant homology with the consensus sequence of the class II family of the endonuclease apurinic-apyrimidinic (AP) proteins. The analysis of the activity of the 40-kDa recombinant protein, named NL1Tc, obtained from the expression of the L1Tc ORF1 in an Escherichia coli "in vitro" expression system revealed that the sequence codes for a protein with endonuclease activity specific for apurinic-apyrimidinic (AP) sites. Data are also presented showing that in vivo expression of the NL1Tc protein conferred viability by complementation to E. coli exonuclease III deletion mutants (BW286 strain). We propose that the biological function of the AP endonuclease activity of the NL1Tc protein may be connected with the introduction into the DNA of free 3' ends that could be used as primers for the integration, along the T. cruzi genome, of the L1Tc element and that the nicking could be a general mechanism for the retrotransposition of non-site-specific non-long terminal repeat retrotransposons.
authors.affiliation: Departamento de Biología Molecular, Instituto de Parasitología y Biomedicina López Neyra, CSIC Calle Ventanilla, 11, 18001 Granada, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Olivares
authors.forename: C
authors.initials: C
authors.lastname: Alonso
authors.forename: M C
authors.initials: MC
authors.lastname: López
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016384:Consensus Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases / Q000737:chemistry*; D005816:Genetic Complementation Test; D008190:Lyases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D018626:Retroelements; D016415:Sequence Alignment; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000235:genetics*
chemical_list: D017931:DNA Primers; D029968:Escherichia coli Proteins; D018626:Retroelements; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D008190:Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase