Abstract
Lysine malonylation (Kmal) is a new post-translational modification (PTM), which has been reported in several prokaryotic and eukaryotic species. Although Kmal can regulate many and diverse biological processes in various organisms, knowledge about this important PTM in the apicomplexan parasite Toxoplasma gondii is limited. In this study, we performed the first global profiling of malonylated proteins in T. gondii tachyzoites using affinity enrichment and Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Three experiments performed in tandem revealed 294, 345, 352 Kmal sites on 203, 236, 230 malonylated proteins, respectively. Computational analysis showed the identified malonylated proteins to be localized in various subcellular compartments and involved in many cellular functions, particularly mitochondrial function. Additionally, one conserved Kmal motif with a strong bias for cysteine was detected. Taken together, these findings provide the first report of Kmal profile in T. gondii and should be an important resource for studying the physiological roles of Kmal in this parasite.
Highlights
Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is estimated to affect approximately one-third of the world population (Montoya and Liesenfeld, 2004)
The number of Kmal proteins in T. gondii was higher than that reported in common wheat, S. erythraea (Xu et al, 2016; Liu et al, 2018), but was lower than that detected in E. coli (Qian et al, 2016), rhizobacterium Bacillus amyloliquefaciens FZB42 (Fan et al, 2017) and mammals (Colak et al, 2015), was close to the number of malonylated proteins identified in Cyanobacteria (Ma et al, 2017)
The finding that 27% of the malonylated proteins were modified at multiple lysine residues/sites is in agreement with the results detected in wheat and S. erythraea (Xu et al, 2016; Liu et al, 2018), indicating some conservation in the level of protein malonylation between T. gondii and other organisms, such as bacteria and plants, the level and site of malonylation may vary among different organisms
Summary
Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is estimated to affect approximately one-third of the world population (Montoya and Liesenfeld, 2004). In order to adapt to different environments and survive inside various tissues within different hosts, the parasite tightly regulates its metabolic and protein functions at the post-translational level (Xiao et al, 2010; Dubey et al, 2017). Post-translational modification of proteins via lysine malonylation (Kmal) has been reported across many metabolic pathways, such as fatty acid synthesis and oxidation (Hirschey and Zhao, 2015), mitochondrial respiration (Xie et al, 2012), glycolysis (Peng et al, 2011; Lin et al, 2012), and modification of histones (Hershko and Ciechanover, 1998). Our data lay the foundation for future investigations into the biological functions of malonylated proteins in T. gondii and in the context of host– parasite interaction
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