The moving junction protein RON4, although not critical, facilitates host cell invasion and stabilizes MJ members

Area of Science:

• Parasitology
• Cell Biology
• Infectious Diseases

Background:

• Toxoplasma gondii, an Apicomplexan parasite, invades host cells using a moving junction (MJ) complex.
• Proteins secreted from rhoptries and micronemes are crucial for MJ complex formation and host cell invasion.
• The assembly mechanism of the AMA1/RON2/4/5/8 MJ complex in T. gondii is not fully understood.

Purpose of the Study:

• To investigate the role of TgRON4 in the assembly of the T. gondii MJ complex.
• To elucidate the function of TgRON4 in host cell invasion by T. gondii.

Main Methods:

• CRISPR-Cas9 gene editing was used to create a TgRON4 knockout mutant in T. gondii strain RH.
• Invasion assays were performed to compare the infectivity of the mutant and wild-type parasites.
• Protein expression levels, specifically of the RON5 N-terminal fragment, were analyzed in the mutant.

Main Results:

• Disruption of TgRON4 resulted in a moderate decrease in host cell invasion efficiency compared to wild-type parasites.
• The absence of TgRON4 led to reduced expression of the endogenous N-terminal fragment of RON5.
• These findings suggest TgRON4 plays a role in the proper assembly and function of the MJ complex.

Conclusions:

• TgRON4 is an important component of the T. gondii MJ complex, influencing both invasion and the expression of other MJ proteins like RON5.
• This study enhances the understanding of MJ complex assembly mechanisms in T. gondii.
• Targeting the MJ complex, including TgRON4, presents a potential strategy for developing novel anti-parasitic therapies.