AUTHOR=He Cheng , Xu Mei-zhen , Pan Shuai , Wang Hui , Peng Hong-juan , Liu Zhuan-zhuan 

TITLE=iTRAQ-Based Phosphoproteomic Analysis of Toxoplasma gondii Tachyzoites Provides Insight Into the Role of Phosphorylation for its Invasion and Egress

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 10 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.586466

DOI=10.3389/fcimb.2020.586466

ISSN=2235-2988

ABSTRACT=The invasion and egress are the two key steps in T. gondii lytic cycle that are vital to the propagation of its infection, and the phosphorylation is believed to play important roles in these processes. However, the phosphoproteome data of T. gondii at these two stages has not been characterized. In this study, we profiled the phosphoproteome data of tachyzoites at the stages of just invading (JI) and prior to egress (PE) based on iTRAQ quantitative analysis. A total of 46 phosphopeptides, 42 phosphorylation sites and 38 phosphoproteins were detected. In addition, 10 phosphoproteins with phosphorylation level significantly changed were identified in the comparison of PE vs. JI. Functional analysis of these identified phosphoproteins suggested that phosphorylation-mediated modulation of protein function was employed to regulate the pathway of toxoplasmosis and metabolism and cellular processes correlated with tachyzoite’s binding, location and so on, and thus play vital roles in the parasite lytic cycle. Moreover, CN (cytoskeletal network)-associated IMCs (Inner Membrane Complex, IMC1, IMC4, IMC6 and IMC12), IVN (Intravascular Network)-related GRAs (Dense Granule, GRA2, GRA3, GRA7 and GRA12) and PVM (Parasitophorous Vacuole Membrane)-localized ROP5 were shown to be enriched at the central nodes in the protein interaction network, in which the phosphorylation level of IMC4, GRA2, GRA3 and GRA12 were found to be significantly regulated. This study revealed the main cellular processes and key phosphoproteins crucial for the invasion and egress of T. gondii, which will provide new insights into the developmental biology of T. gondii in vitro and contribute to the understanding of pathogen-host interactions from the parasite perspective.