Chloramphenicol-sensitive mitochondrial translation in Trypanosoma brucei

We developed an in organello system to label newly synthesized mitochondrially encoded proteins of Trypanosoma brucei. Highly purified mitochondria, prepared under isotonic conditions, were incubated with radioactive methionine and cysteine in a suitable translation buffer. Analysis of mitochondrial extracts on TRIS-Tricine gels revealed a subset of labeled, NP-40-insoluble proteins. The labeling of these proteins was resistant to the cytosol-specific translation inhibitor cycloheximide. The proteins, however, were not labeled in the presence of chloramphenicol or erythromycin, inhibitors of prokaryotic type translation, or puromycin, a general translation inhibitor. These results indicate that isotonically isolated mitochondria of T. brucei are capable of protein synthesis.