RIBOSOMES OF LEISHMANIA ARE A TARGET FOR THE AMINOGLYCOSIDES

Ribosomes of Leishmania, a parasitic protozoan (member of the order of Kinetoplastidae), were purified on a sucrose density gradient. Two di fferent types of ribosomes were isolated from the promastigotes: cytop lasmic (88S and 91S from L. tropica and L. donovani, respectively) and mitochondrial (75S in both species). Both types of ribosome dissociat ed into their subunits at low Mg2+ concentration (1-2 mM) as follows: 67S and 49S for the 91S cytoplasmic ribosomes of L. donovani and 61S a nd 43S for the 88S cytoplasmic ribosome of L. tropica; 55S and 34S for L. tropica and 60S and 39S for L. donovani mitochondrial ribosomes, r espectively. Paromomycin (aminosidine), an aminoglycoside aminocyclito l antibiotic, interacted with the ribosomes to promote the association of the subunits. Under similar experimental conditions, spermidine an d pentamidine were inactive.