Establishment of improved genetically encoded fluorescence-based biosensors to monitor redox and energy dynamics in the malaria parasite Plasmodium falciparum

Abstract

The development of genetically encoded fluorescence-based biosensors has started a new era in redox biology research, allowing non-invasive monitoring of specialized redox couples such as glutathione, NADP(H), and NAD(H). Former obstacles, for example, the introduction of artifacts, impossibility of dynamic measurements, low selectivity, and non-reversibility, could be overcome with this technology. Redox research and studying the associated ROS have attracted more and more attention in recent years. The dual role of ROS, which on the one hand are essential in signal transduction but on the other hand can also lead to severe diseases resulting from an imbalance between ROS and the antioxidant capacity of the cell, is the focus of attention. ROS also play a central role in one of the most life-threatening diseases–malaria. During its complex life cycle, the malaria parasite Plasmodium is exposed to substantial redox challenges. The oxidative burden on the parasite can be increased to such an extent via inhibition of central metabolic processes, such as the polymerization of hemozoin that the parasites’ antioxidative system can no longer sufficiently counteract the development of ROS, which ultimately leads to the death of the parasite. This circumstance has been exploited in the development of numerous antimalarial drugs currently used. However, the development of resistance mechanisms against established and frequently used drugs is a growing global health problem. Research into new control strategies continues to be essential as the risk of vector-borne diseases, especially malaria, has increased due to the global warming that human activities have induced. Changes in the ecosystem and climate, political instability, health policies, and the resulting increased refugee migration from endemic countries make the fight against malaria a global issue. The development of new, effective drugs and understanding the emergence of resistance mechanisms are therefore indispensable. Genetically encoded sensors can play an important role in answering the questions of which metabolic pathways an agent targets, which specific redox couples are affected, and whether this differs between drug-sensitive and -resistant parasite lines. In the context of this work, important findings for sensor development could be obtained. The repertoire of biosensors stably integrated into Plasmodium parasites could be extended, and an improved measuring method could be established, thereby allowing the drug-induced effects on various redox couples to be monitored to a broader extent.