Sequences of three Trypanosoma congolense maxicircle genes allow prediction of regions encoding transcripts that undergo extensive RNA editing

We have mapped the mitochondrial (maxicircle) genome of Trypanosoma congolense and sequenced a 2.07-kb region spanning the 3' 277 nt of the NADH dehydrogenase subunit 8 (ND8) gene, all of the ND9 (previously called CR2; Souza, et al., submitted), unidentified sequence (US), ND7, and cytochrome oxidase subunit subunit III (COIII) genes, and the 5' 83 nt of the apocytochrome b (CYb) gene. Comparison of ND8, ND7, and CYb DNA and edited RNA sequences of T. congolense to those of the related kinetoplastid, T. brucei, revealed that regions encoding transcripts which undergo RNA editing have distinctive patterns of sequence divergence (Read, et al., submitted). Within protein coding regions, transitions occur at approximately 10% of non-thymidine (non-T) nucleotides (nts) and transversions are extremely rare. More importantly, the number of Ts in 10-12% of editing sites (ESs; sites between non-T nts) in these genes differs between the two species. In the regions of CYb, ND7 and ND8 examined, RNA editing [1] compensates for the differ-