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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Cell. Infect. Microbiol. | doi: 10.3389/fcimb.2019.00307

iTRAQ-based Global Phosphoproteomics Reveals Novel Molecular Differences Between Toxoplasma gondii Strains of Different Genotypes

  • 1Lanzhou Veterinary Research Institute (CAAS), China
  • 2Department of Parasitology, School of Basic Medical Sciences, Shandong University, China
  • 3European Bioinformatics Institute (EMBL-EBI), United Kingdom
  • 4State Key Laboratory of Veterinary Etiological Biology, Lanzhou Institute of Veterinary Research (CAAS), China
  • 5College of Veterinary Medicine, Yunnan Agricultural University, China
  • 6Faculty of Medicine and Health Sciences, University of Nottingham, United Kingdom

To gain insights into differences in the virulence among T. gondii strains at the posttranslational level, we conducted a quantitative analysis of the phosphoproteome profile of T. gondii strains belonging to three different genotypes. Phosphopeptides from the three strains type I (RH strain), type II (PRU strain), and PYS strain (Chinese ToxoDB#9) were enriched by titanium dioxide (TiO2) affinity chromatography and quantified using iTRAQ technology. A total of 1,441 phosphopeptides, 1,250 phosphorylation sites and 759 phosphoproteins were detected. In addition, 392, 298 and 436 differentially expressed phosphoproteins (DEPs) were identified in RH strain when comparing RH/PRU strains, in PRU strain when comparing PRU/PYS strains, and in PYS strain when comparing PYS/RH strains, respectively. Functional characterization of the DEPs using GO, KEGG and STRING analyses revealed marked differences between the three strains. In silico kinase substrate motif analysis of the DEPs revealed three (RxxS, SxxE and SxxxE), three (RxxS, SxxE, and SP) and five (SxxE, SP, SxE, LxRxxS and RxxS) motifs in RH strain when comparing RH/PRU strains, in PRU strain when comparing PRU/PYS, and in PYS strain when comparing PYS/RH strains, respectively. This suggests that multiple overrepresented protein kinases including PKA, PKG, CKII, IKK, and MAPK could be involved in such a difference between T. gondii strains. Kinase associated network analysis showed that ROP5, ROP16 and cell-cycle-associated protein kinase CDK were the most connected kinase peptides. Our data reveal significant changes in the abundance of phosphoproteins between T. gondii genotypes, which explain some of the mechanisms that contribute to the virulence heterogeneity of this parasite.

Keywords: Toxoplasma gondii, Genotype, tachyzoite, iTRAQ, phosphoproteomics, Differentially expressed phosphoproteins

Received: 10 May 2019; Accepted: 09 Aug 2019.

Edited by:

Tiago W. Mineo, Federal University of Uberlandia, Brazil

Reviewed by:

Bellisa F. Barbosa, Federal University of Uberlandia, Brazil
Hayley Bullen, Burnet Institute, Australia  

Copyright: © 2019 Wang, Zhou, Calderón-Mantilla, Petsalaki, He, Song, Elsheikha and Zhu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Xing-Quan Zhu, State Key Laboratory of Veterinary Etiological Biology, Lanzhou Institute of Veterinary Research (CAAS), Lanzhou, Gansu Province, China, xingquanzhu1@hotmail.com