Characterization of a novel translational inhibitor from Leishmania mexicana promastigotes.

An inhibitory activity blocking protein synthesis elongation in several eukaryotic systems has been detected in Leishmania mexicana extracts. This factor, which competes with aminoacylation of tRNA and also affects the subsequent polymerization step, is a strong inhibitor of polypeptide synthesis induced by poly U in wheat-germ extracts or by endogenous mRNAs in rat liver cell-free systems. The purified translational inhibitor has shown to be essentially free of proteins. Several chemical and biochemical properties of the inhibition factor have supported the conclusion that it behaves as a 200 bases RNA with a high content of secondary structure.