Improvements on the quantitative analysis of Trypanosoma cruzi histone post translational modifications: Study of changes in epigenetic marks through the parasite's metacyclogenesis and life cycle.

Trypanosome histone N-terminal sequences are very divergent from the other eukaryotes, although they are still decorated by post-translational modifications (PTMs). Here, we used a highly robust workflow to analyze histone PTMs in the parasite Trypanosoma cruzi using mass spectrometry-based (MS-based) data-independent acquisition (DIA). We adapted the workflow for the analysis of the parasite's histone sequences by modifying the software EpiProfile 2.0, improving peptide and PTM quantification accuracy. This workflow could now be applied to the study of 141 T. cruzi modified histone peptides, which we used to investigate the dynamics of histone PTMs along the metacyclogenesis and the life cycle of T. cruzi. Global levels of histone acetylation and methylation fluctuates along metacyclogenesis, however most critical differences were observed between parasite life forms. More than 66 histone PTM changes were detected. Strikingly, the histone PTM pattern of metacyclic trypomastigotes is more similar to epimastigotes than to cellular trypomastigotes. Finally, we highlighted changes at the H4 N-terminus and at H3K76 discussing their impact on the trypanosome biology. Altogether, we have optimized a workflow easily applicable to the analysis of histone PTMs in T. cruzi and generated a dataset that may shed lights on the role of chromatin modifications in this parasite.