TRYPANOSOMA-BRUCEI TBRGG1, A MITOCHONDRIAL OLIGO(U)-BINDING PROTEIN THAT COLOCALIZES WITH AN IN-VITRO RNA EDITING ACTIVITY

We report the characterization of a Trypanosoma brucei 75-kDa protein of the RGG (Arg-Gly-Gly) type, termed TBRGG1, Dicistronic and monocist ronic transcripts of the TBRGG1 gene were produced by both alternative splicing and polyadenylation, TBRGG1 was found in two or three forms that differ in their electrophoretic mobility on SDS-polyacrylamide ge l electrophoresis gels, one of which was more abundant in the procycli c form of the parasite. TBRGG1 was localized to the mitochondrion and appeared to be more abundant in bloodstream intermediate and stumpy fo rms in which the mitochondrion reactivates and during the procyclic st age, which possesses a fully functional mitochondrion. This protein wa s characterized to display oligo(U) binding characteristics and was fo und to co-localize with an in vitro RNA editing activity in a sediment ation analysis. TBRGG1 most likely corresponds to the 83-kDa oligo (U) -binding protein previously identified by UV cross-linking of guide RN A to mitochondrial lysates (Leegwater, P,, Speijer, D,, and Benne, R, (1995) fur. J, Biochem, 227, 780-786).