Genome-wide profiling of tRNA modifications reveal the presence of divergent signatures in Plasmodium falciparum

tRNAs are known to be extensively decorated with various nucleotide modifications, which can modulate the biological properties of tRNAs, such as promoting translation efficiency or fidelity, influencing codon preference and stabilizing tertiary structure of tRNAs. Dynamic alteration of the tRNA modifications, particularly under stress, are conserved gene regulatory mechanisms employed by cells across the kingdoms of life. The malaria-causing Plasmodium falciparum, which has a highly AT-biased genome, is reliant on a non-redundant set of tRNA genes to decode distinct and codon-skewed transcriptomes across its developmental stages. This genomic feature highlights the regulatory potential of tRNA modifications and warrants studies on how the tRNA epitranscriptome can impact gene regulatory function in this parasite. However, systematic studies of tRNA modifications in P. falciparum remain sporadic. In this study, we present a sequencing-based analysis of tRNA modifications in P. falciparum through optimizing the TGIRT-tRNA sequencing approach. The optimized protocol significantly reduces reverse transcription (RT) stop-induced short reads and enhances full-length cDNA synthesis, enabling the identification and stoichiometric estimation of a select nucleotide modifications at single-base resolution. We were able to identify seven types of conserved tRNA modifications and discovered two non-canonical signatures at A59 and U73 positions on specific nuclear-encoded tRNAs, which provides new insights into previously unreported modification sites. Our findings further reveal the dynamic nature of tRNA modifications during stage progression and under stress conditions.