plasmepsin

Plasmepsins are a family of aspartic proteases produced by malaria-causing Plasmodium species, most notably Plasmodium falciparum. They belong to the pepsin-like class of proteases and share the characteristic two catalytic aspartate residues that drive proteolysis. In P. falciparum, several plasmepsins have been described, with plasmepsins I through IV forming the principal group involved in the parasite’s hemoglobin degradation pathway.

In the parasite’s digestive vacuole, plasmepsins I–IV participate in the proteolysis of host hemoglobin that has been endocytosed by the parasite. Their activity is part of a coordinated cascade of proteolysis that releases amino acids essential for parasite growth and generates peptide fragments that are further processed by other proteases, such as falcipains and aminopeptidases. This hemoglobin digestion provides nutrients and contributes to heme detoxification through downstream pathways.

Beyond their role in hemoglobin degradation, additional plasmepsins have different cellular functions. For example, plasmepsin V, located in the parasite’s endoplasmic reticulum, processes exported proteins bearing the PEXEL motif, enabling their trafficking across the parasitophorous vacuole membrane into the host erythrocyte. This function is important for parasite remodeling of the host cell and virulence.

Plasmepsins are studied as potential antimalarial drug targets because they are parasite-specific proteases with distinct catalytic mechanisms. Research has explored various inhibitors, aiming to block parasite growth; however, challenges such as redundancy among family members and the need for selective targeting remain.