Inhibitory Compounds Targeting Plasmodium falciparum Gyrase B

Area of Science:

• Biochemistry
• Parasitology
• Drug Discovery

Background:

• Malaria remains a significant global health issue due to drug resistance and limited vaccine availability.
• DNA gyrase, a validated antibacterial target, is present in the apicoplast of Plasmodium falciparum, suggesting its potential as an antimalarial target.
• Challenges in purifying the GyrA subunit have hindered the study and screening of malarial DNA gyrase.

Purpose of the Study:

• To identify novel antimalarial compounds targeting Plasmodium falciparum DNA gyrase.
• To overcome challenges in reconstituting the malarial DNA gyrase holoenzyme for screening.

Main Methods:

• A hybrid enzyme approach was used, combining Plasmodium falciparum GyrB with Escherichia coli GyrA.
• A library of compounds specific for P. falciparum GyrB was screened against the hybrid enzyme.
• In vitro assays measured supercoiling activity, DNA binding, and ATP hydrolysis. Purpurogallin's binding affinity to P. falciparum GyrB was assessed.

Main Results:

• Two compounds inhibited the hybrid enzyme's supercoiling activity more than the E. coli enzyme.
• Purpurogallin (PPG) was identified as a preferential inhibitor, disrupting DNA binding to the gyrase complex.
• PPG reduced DNA-induced ATP hydrolysis and demonstrated higher binding affinity to P. falciparum GyrB compared to E. coli GyrA.
• PPG exhibited inhibitory effects against the malaria parasite in vitro.

Conclusions:

• Purpurogallin (PPG) inhibits Plasmodium falciparum DNA gyrase by interacting with the GyrB subunit, disrupting DNA binding and reducing ATPase activity.
• PPG shows potential as a novel antimalarial agent for further development.
• The hybrid enzyme system provides a viable method for screening inhibitors of malarial DNA gyrase.