CHARACTERIZATION OF 2 NUCLEAR-ENCODED PROTEIN-COMPONENTS OF MITOCHONDRIAL RIBONUCLEOPROTEIN COMPLEXES FROM LEISHMANIA-TARENTOLAE

Two mitochondrial proteins with molecular masses of 18 and 51 kDa were isolated from Leishmania tarentolae, and N-terminal amino-acid sequen ces were obtained. The cDNAs and genes encoding these proteins were cl oned using RT-PCR. The proteins were identified as components of the p reviously characterized mitochondrial ribonucleoprotein complexes, T-I a and T-VI, by comigration in native gels. The p18 and p51 genes conta in 17 and 9-amino-acid N-terminal sequences, which are not present in the mature proteins and may represent cleavable mitochondrial targetin g sequences. There are two identical pls genes separated by 1.7 kb in tandem array and both are transcribed. The p18 amino-acid sequence is not similar to any sequence in the database. Antiserum to p18 expresse d in Escherichia coli reacts with the entire tubular mitochondrion. Th e p51 gene is single copy, and the amino-acid sequence is similar to m itochondrial aldehyde dehydrogenases from other organisms. The N-termi nal amino-acid sequences of 71 and 62-kDa mitochondrial proteins which co-migrated in native gels with several other T-complexes were also o btained. The p71 sequence proved to be similar to hsp70 sequences from other organisms. The p62 sequence was identical to an hsp60 sequence from Trypanosoma brucei.