The non-LTR (long terminal repeat) retrotransposon L1Tc from Trypanosoma cruzi codes for a protein with RNase H activity Rodríguez Heras, Sara The deduced amino acid sequence of the region downstream of the reverse transcriptase (RT) motif of the Trypanosoma cruzi L1Tc non-LTR retrotransposon shows a significant homology with the sequence coding for proteins with RNase H activity from different organisms and retroelements. The 25-kDa His6-tagged recombinant protein bearing only the L1Tc RNase H domain, named RHL1Tc, exhibits RNase H activity as measured on the [3H]poly(rA)/poly(dT) hybrid used as substrate as well as on specific homologous and heterologous [32P]RNA/DNA hybrids. The mutation of the conserved aspartic acid at position 39 of the enzyme catalytic site, but not of the serine at position 56 (non-conservative amino acid), abolishes protein RNase H activity. The RNase H activity of the RHL1Tc protein is Mg2 -dependent, and it is also active in the presence of the Mn2  ion. The optimal condition of RNase H activity is found at pH 8 and 37 °C, although it also has significant enzymatic activity at 19 °C and pH 6. However, it cannot be excluded that the RNase H activity level and its optimal conditions may be different from that of a protein containing both RT and RNase H domains. 2024-02-06T12:46:55Z 2024-02-06T12:46:55Z 2002 journal article Olivares M, García-Pérez JL, Thomas MC, Heras SR, López MC. The non-LTR (long terminal repeat) retrotransposon L1Tc from Trypanosoma cruzi codes for a protein with RNase H activity. J Biol Chem. 2002 Aug 2;277(31):28025-30. doi: 10.1074/jbc.M202896200 https://hdl.handle.net/10481/88464 10.1074/jbc.M202896200 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elseivier