Non-histone protein methylation inTrypanosoma cruziepimastigotes

Abstract

Post-translational methylation of proteins, which occurs in arginines and lysines, modulates several biological processes at different levels of cell signaling. Recently, methylation has been demonstrated in the regulation beyond histones, for example, in the dynamics of protein-protein interaction and protein-nucleic acid. Mass spectrometry-based proteomics has allowed a large-scale identification of protein methylation - mainly in arginine residues -, in different organisms, including some trypanosomes. However, the presence and role of protein methylation in Trypanosoma cruzi, the etiologic agent of Chagas disease, has not yet been elucidated. In this work, we applied mass spectrometry and described the arginine and lysine methylproteome of T. cruzi. In epimastigotes, 1336 methylsites (657 methyl-arginines and 679 methyl-lysines) in 878 methylated proteins were identified by LC-MS/MS. Our functional and interaction analyzes show that protein methylation impacts different biological processes, with emphasis on translation. Separately, protein arginine methylation is related to oxireduction and carbohydrate metabolism, while lysine methylation impacts the protein synthesis. In addition, 50 methylated proteins have been previously described with phosphorylation sites in T. cruzi, represented by RNA binding proteins, sterol methyltransferase activity and calpain peptidases, indicating the possibility of crosstalk in the regulation of these proteinsThis work represents the first proteomic analysis of T. cruzi methylproteome and is the first to characterize lysine methylation in trypanosomatids. Collectively, these data inform about new fundamental biological aspects of this organism impacted by protein methylation, that can contribute to the identification of pathways and key pieces in the biology of this human pathogen.

A mitochondrial SET domain protein is essential inT. bruceiand required for mitochondrial morphology and function

“…While the conditions used in our immunoprecipitations did not allow us to assess methylation, nine of the proteins identified in our pulldowns were methylated in T. cruzi epimastigotes. Most of these shared proteins were involved in translation ( Table 2, bold italics ) (28).…”

“…First recognized for modifying histones, it is now clear that SET domain PKMTs can catalyze methylation of many non-histone substrates including tumor suppressors, proteins involved in signaling pathways and translation, and transcription factors (6). In the single study of protein lysine methylation in trypanosomes, methylated lysine residues were identified in proteins related to translation, stress response, glycolytic processes, amino acid transport, and cellular metabolism (7) . The role that SET domain PKMTs play in kinetoplastid biology, especially through the modification of non-histone proteins, is unknown.…”