THE MITOCHONDRIAL ND8 GENE FROM CRITHIDIA-ONCOPELTI IS NOT PAN-EDITED

RNA editing in trypanosomatid mitochondria is a process involving the insertion and deletion of uridine residues within the coding region of maxicircle messenger RNA transcripts, Twelve of the 17 known genes ne ed editing to produce functional molecules. We have analyzed the predi cted editing sites for the Crithidia oncopelti mitochondrial NADH-ubiq uinone oxidoreductase subunit 8 (ND8) gene based on known mRNAs from o ther trypanosomatid species. All studied ND8 mRNAs undergo editing thr oughout the coding land 3' noncoding) sequences (pan-editing), The 5' part of the C, oncopelti ND8 gene undergoes editing (like in Leishmani a tarentolae and Trypanosoma (brucei) while the 3' part of the pre-edi ted gene corresponds to the 3' part of edited ND8 mRNAs from other org anisms. The organization of the ND8 gene in C, oncopelti mitochondrial DNA differs from all organisms investigated so far - this gene is not pan-edited, We have also localized the guide RNA for cytochrome b bet ween 9S rRNA and the ND8 gene. This RNA shows high homology to the gCY b-II gene of L. tarentolae and the gCyb gene of Crithidia fasciculata. A hypothetical editing pattern for the cytochrome b gene in C. oncope lti maxicircles is proposed. (C) 1998 Federation of European Biochemic al Societies.