Cloning and characterization of a DNA polymerase β gene from Trypanosoma cruzi

A gene coding for a DNA polymerase β from the Trypanosoma cruzi Miranda clone, belonging to the TcI lineage, was cloned (Miranda Tcpolβ), using the information from eight peptides of the T. cruzi β-like DNA polymerase purified previously. The gene encodes for a protein of 403 amino acids which is very similar to the two T. cruzi CL Brener (TcIIe lineage) sequences published, but has three different residues in highly conserved segments. At the amino acid level, the identity of TcI-polβ with mitochondrial polβ and polβ-PAK from other trypanosomatids was between 68–80% and 22–30%, respectively. Miranda Tc-polβ protein has an N-terminal sequence similar to that described in the mitochondrial Crithidia fasciculata polβ, which suggests that the TcI-polβ plays a role in the organelle. Northern and Western analyses showed that this T. cruzi gene is highly expressed both in proliferative and non-proliferative developmental forms. These results suggest that, in addition to replication of kDNA in proliferative cells, this enzyme may have another function in non-proliferative cells, such as DNA repair role similar to that which has extensively been described in a vast spectrum of eukaryotic cells.