Phosphoribulokinase (PRK) (PRK)

Phosphoribulokinase (PRK) is an essential enzyme in the Calvin-Benson-Bassham (CBB) cycle, which is the primary pathway for carbon fixation in photosynthetic organisms such as plants, algae, and cyanobacteria [6, 20, 35]. It catalyzes the final step of the regenerative phase of the cycle, using ATP to phosphorylate ribulose 5-phosphate into ribulose 1,5-bisphosphate, the substrate for CO2 capture by Rubisco [6, 8]. Interestingly, PRK is also present in the apicoplast of apicomplexan parasites like Plasmodium falciparum, the causative agent of malaria, where it remains vital for parasite survival despite the loss of photosynthetic capacity [11, 16]. Because this enzyme is entirely absent in humans and other mammals, it represents a highly specific therapeutic target for the development of new antimalarial and antimicrobial drugs with a low risk of host toxicity [13, 16]. Regulation of PRK varies significantly between species; eukaryotic PRK is often redox-regulated via thioredoxin and the CP12 protein, while prokaryotic versions are regulated by allosteric effectors like NADH and AMP [8, 19, 20, 35]. Small molecules such as 6-phosphogluconate and isocitrate have been identified as inhibitors that compete with the substrate or bind allosterically to disrupt enzymatic activity [6, 7, 33]. In the context of herbicide development, substances like alpha-terthienyl have been shown to down-regulate PRK expression, leading to the inhibition of photosynthesis and plant death [21]. Current research efforts are focused on identifying potent small-molecule inhibitors that can selectively target the parasite enzyme or disrupt the regulatory complexes essential for its function [7, 19, 20].

Other names

PhosphopentokinasePRKaseRibulose-5-phosphate kinase

Inhibition of the ATP-dependent phosphorylation of ribulose 5-phosphate to ribulose 1,5-bisphosphate, thereby disrupting the Calvin cycle or apicoplast metabolism.