A first-in-Plasmodiumstudy on tRNA intron splicing endonuclease ‘PfTSEN1’ and its substrate expression in clinical stage malaria

Mature tRNAs play critical role in several cellular processes including protein translation, post-translational-modifications and programmed-cell-death. Maturation of pre-tRNAs require removal of 5’-leaders, 3’-trailers, splicing of introns and addition of conserved 3’-terminal CCA sequence. The tRNA splicing mechanism, an essential step in tRNA maturation govern by a tRNA splicing endonuclease. While the existence of functional tRNA splicing endonuclease(s) in Plasmodium falciparum has not been identified, its significance in other eukaryotes suggests a potential role in tRNA splicing event. Our study identified total tRNAs in Plasmodium and characterize a Pf tRNA splicing endonuclease (annotated as Pf TSEN1) recognised recently as a component of ribonucleoprotein (RNP) complex, and synthesized a naphthoquinone derivative as a novel anti-malarial compound (‘TSEN i ’) targeting the functional activity of this protein. Enzyme activity assays elucidated that Pf TSEN1 catalyses splicing of in vitro transcribed pre-tRNA leu , the expression of which was confirmed during the clinical stages of malaria parasite by RT-PCR. Interestingly, TSEN i binds to and inhibits enzymatic activity of Pf TSEN1, and showed potent anti-malarial activity against chloroquine-sensitive 3D7 and resistant strains Dd2 of P. falciparum . Overall, our study deliver key knowledge towards the functional role of Pf tRNA splicing endonuclease, and its inhibitor TSEN i as potent anti-malarial.