The L1Tc, long interspersed nucleotide element from Trypanosoma cruzi, encodes a protein with 3 '-phosphatase and 3 '-phosphodiesterase enzymatic activities

The presence of a long interspersed nucleotide element, named L1Tc, which i s actively transcribed in the parasite Trypanosoma cruzi, has been recently described. The open reading frame 1 of this element encodes the NL1Tc prot ein, which has apurinic/apyrimidinic endonuclease activity and is probably implicated in the first stage of the transposition of the element. In the p resent paper we show that NL1Tc effectively removes 3'-blocking groups (3'- phosphate and 3'-phosphoglycolate) from damaged DNA substrates. Thus, both 3'-phosphatase and 3'-phosphodiesterase activities are present in NL1Tc. We propose that these enzymatic activities would allow the 3'-blocking ends t o function as targets for the insertion of L1Tc element, in addition to the apurinic/apyrimidinic sites previously described. The potential biological function of the NL1Tc protein has also been evidenced by its ability to re pair the DNA damage induced by the methyl methanesulfonate alkylating or ox idative agents such as hydrogen peroxide and t-butyl hydroperoxide in Esche richia coli (xth and xth, nfo) mutants.