Protein palmitoylation has been shown to be an important post-translational modification in eukaryotic cells. This modification alters the localization and/or the function of the targeted protein. In the recent years protein palmitoylation has risen in importance in apicomplexan parasites as well. In Toxoplasma gondii, some proteins have been reported to be modified by palmitate. With the development of new techniques that allow the isolation of palmitoylated proteins, this significant post-translational modification has begun to be studied in more detail in T. gondii. Here we describe the palmitoylome of the tachyzoite stage of T. gondii using a combination of the acyl-biotin exchange chemistry method and mass spectrometry analysis. We identified 401 proteins found in multiple cellular compartments, with a wide range of functions that vary from metabolic processes, gliding and host-cell invasion to even regulation of transcription and translation. Besides, we found that more rhoptry proteins than the ones already described for Toxoplasma are palmitoylated, suggesting an important role for this modification in the invasion mechanism of the host-cell. This study documents that protein palmitoylation is a common modification in T. gondii that could have an impact on different cellular processes. Table S1: List of all non-redundant identified candidate proteins from the three independent ABE assays. The first worksheet tab contains a multiconsensus analysis showing proteins identified in all three assays together with their respective mass spectrometry information and in silico predictions. Highlighted in blue are those already described to palmitoylated, in grey are those predicted to be palmitoylated but without experimental evidence and in green those that have homology to known S-acylated proteins from P. falciparum. Tabs 2, 3 and 4 contain particular information and NRP calculations for each assay, while the last tab is a summary of the calculated NRP HA+/HA-ratios calculated for each protein.

No abstract

Graphical abstractInvestigation of type II fatty acid and isoprenoid biosyntheses in Babesia resulted in the identification of two major components within the apicoplastic lumen.Highlights► This study illustrates a four membrane babesid apicoplast. ► Babesia bovis apicoplast resides adjacent to the nucleus. ► Acyl carrier protein and LytB are transcribed and translated in Babesia bovis. ► Isoprenoid biosynthesis likely exists in Babesia bovis. ► Type II fatty acid biosynthesis may not be present in Babesia bovis.