Protease activities of Acanthamoeba polyphaga and Acanthamoeba castellanii

Area of Science:

• Microbiology
• Biochemistry
• Parasitology

Background:

• Acanthamoeba species are protozoan parasites implicated in severe human diseases.
• Proteases are suspected virulence factors in Acanthamoeba infections.
• Limited biochemical characterization exists for Acanthamoeba proteases.

Purpose of the Study:

• To biochemically characterize proteases from Acanthamoeba castellanii and Acanthamoeba polyphaga.
• To investigate the role of proteases in Acanthamoeba pathogenesis.
• To identify the types and activity levels of proteases in Acanthamoeba.

Main Methods:

• Protease activity was assessed using gelatin zymography (SDS-PAGE copolymerized with gelatin).
• Protease inhibitors were used to determine enzyme families.
• Protease activity was evaluated across different pH levels.
• Inhibition of protease activity on Madin-Darby canine kidney (MDCK) cell monolayers was tested.

Main Results:

• Seventeen distinct protease activity bands were identified across two Acanthamoeba species.
• Protease activity bands ranged from 30 to 188 kDa in A. castellanii and 34 to 144 kDa in A. polyphaga.
• Protease activity patterns varied with pH and between species, with A. castellanii exhibiting higher activity.
• Serine proteases were the predominant type, followed by cysteine proteases.
• Aprotinin inhibited Acanthamoeba crude extract protease activity on MDCK cells.

Conclusions:

• Acanthamoeba proteases are diverse, with serine proteases being most prevalent.
• Protease activity is species-specific and pH-dependent.
• Acanthamoeba proteases contribute to virulence by degrading host cells, as evidenced by MDCK monolayer assays.
• Further research into Acanthamoeba protease complexity is warranted for understanding pathogenesis.