CHARACTERIZATION OF KINETOPLAST DNA MINICIRCLES IN TRYPANOSOMA-RANGELI

Kinetoplast DNA, the mitochondrial DNA of kinetoplastid protozoans, is a network of interlocked minicircles and maxicircles. We analyzed the sequence organization of minicircle DNAs in the El Tocuyo strain and the San Augustin clone B6 of Trypanosoma rangeli. The frequencies of d ifferent minicircle types, as defined by the number of 136-bp conserve d regions (CRs), are different in the two strains. About half of the 1 .7-kb T. rangeli El Tocuyo minicircles have 1 CR and most of the other s have 2. In contrast, most of the 1.6-kb T. rangeli San Augustin mini circles have 2 CRs, while some have four. The CR contains a replicatio n origin at one end and is conserved both within and between the two s trains. Comparisons of the T. rangeli El Tocuyo and T. rangeli San Aug ustin minicircle CRs with minicircle CRs of other kinetoplastid specie s reveal that they are most similar to those of Trypanosoma cruzi.