Monday, January 16, 2017

A human proteome array approach to identifying key host proteins targeted by Toxoplasma kinase ROP18

 2017 Jan 13. pii: mcp.M116.063602. doi: 10.1074/mcp.M116.063602. [Epub ahead of print]

Yang Z1Hou Y1Hao T1Rho HS2Wan J2Luan Y1Gao X1Yao J1Pan A1Xie Z1Qian J2Liao W1Zhu H2Zhou X3.


Toxoplasma kinase ROP18 is a key molecule responsible for the virulence of Toxoplasma gondii; however, the mechanisms by which ROP18 exerts parasite virulence via interaction with host proteins remain limited to a small number of identified substrates. To identify a broader array of ROP18 substrates we successfully purified bioactive mature ROP18 and used it to probe a human proteome array. Sixty-eight new putative host targets were identified. Functional annotation analysis suggested that these proteins have a variety of functions including metabolic process, kinase activity and phosphorylation, cell growth, apoptosis and cell death, and immunity, indicating a pleiotropic role of ROP18 kinase. Among these proteins, four candidates, p53, p38, UBE2N, and Smad1 were further validated. We demonstrated that ROP18 targets p53, p38, UBE2N, and Smad1 for degradation. Importantly, we demonstrated that ROP18 phosphorylates Smad1 Ser187 to trigger its proteasome-dependent degradation. Further functional characterization of the substrates of ROP18 may enhance understanding of the pathogenesis of Toxoplasma infection and providing new therapeutic targets. Similar strategies could be used to identify novel host targets for other microbial kinases functioning at the pathogen-host interface.


Kinases*; Microbiology; Pathogens; Protein array; Protein-Protein Interactions*; host-pathogen interaction; proteome array

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