Characterization of the gene encoding the catalytic subunit of the DNA polymerase alpha from Toxoplasma gondii

The gene encoding the catalytic subunit of the Toxoplasma gondii DNA polymerase alpha enzyme has been isolated. The coding region is 6487 bp in length, containing three introns, and specifies a protein of 1690 aa. The seven conserved regions which characterize the polalpha polypeptide, as well as four of the five polalpha-specific aa domains, were found in the T. gondii gene. The absence of one of these domains, as well as the presence of a unique cysteine cluster between domains IV and B in the T. gondii polalpha, may result in a slight difference in the secondary or even tertiary structure compared with the human homologue and thus may be suitable for designing anti-Toxoplasma drugs. A number of amino acid differences within the seven conserved regions between the human and T. gondii polalpha, as well as variations in the spacings of these regions, were also observed.