A new release on life: emerging concepts in proteolysis and parasite invasion

Area of Science:

• Parasitology
• Molecular Biology
• Biochemistry

Background:

• Apicomplexan parasites like Plasmodium (malaria) and Toxoplasma invade host cells using specialized surface proteins (ZSPs).
• Proteolysis, or protein breakdown, plays a crucial role in the invasion process, particularly in modifying ZSPs for attachment and penetration.
• The exact proteases and mechanisms involved in ZSP processing during invasion are not fully understood.

Purpose of the Study:

• To explore the emerging conceptual framework for the role of proteolysis in apicomplexan cell invasion.
• To investigate the proposed mechanisms of ZSP processing, including primary activation and secondary shedding (shaving or capping).
• To identify potential roles for Rhomboid family proteases in the intramembrane cleavage of ZSPs and discuss their significance in parasite invasion.

Main Methods:

• Literature review and synthesis of existing research on ZSP processing and proteolysis in apicomplexan parasites.
• Analysis of proposed models for ZSP shedding, distinguishing between shaving and capping mechanisms.
• Discussion of evidence supporting intramembrane cleavage of ZSPs by Rhomboid proteases.

Main Results:

• ZSPs are processed through primary activation (trimming/fragmentation) and secondary shedding (shaving/capping) during invasion.
• ZSPs can be cleaved either adjacent to or within the membrane anchor.
• Evidence suggests integral membrane serine proteases of the Rhomboid family may catalyze intramembrane cleavage of ZSPs.

Conclusions:

• Sequential proteolytic events are critical for apicomplexan parasite invasion, involving activation and shedding of ZSPs.
• Intramembrane cleavage by Rhomboid proteases is a proposed mechanism for ZSP release, particularly for adhesive ligands.
• Targeting these proteolytic pathways could lead to novel synergistic anti-parasitic therapies against diseases like malaria and toxoplasmosis.