Site specific pseudouridine (Psi) on Leishmania rRNA regulates translation of subset of proteins

Leishmania are unicellular parasites that cycle between the insect and mammalian host and is the causative agent of Leishmaniasis. Previous studies from our lab suggested that individual rRNA modification such as pseudouridine (Psi) and 2-O-methylation are developmentally regulated during the complex life cycle of these parasites. Ablation of a single snoRNA guiding Psi in the inter-subunit bridge, helix69 of the ribosome affects its affinity to translate specific mRNA. Mutational analysis in the pseudouridylation pocket of this snoRNA supports the notion that the guided modification and not the chaperone activity, is essential for the observed phenotype. Structural studies using CryoEM suggested that a single Psi modification can affect the rRNA structure. We propose that alteration in rRNA modifications could generate ribosomes preferentially translating state-beneficial proteins.