Chemical proteomics approach reveals the direct targets and the heme-dependent activation mechanism of artemisinin in Plasmodium falciparum using an activity-based artemisinin probe
Authors:Jigang Wang1,2,# and Qingsong Lin2
doi: 10.15698/mic2016.05.503
Volume 3, pp. 230 to 231, published 05/04/2016.
1 The State Key Laboratory of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing 210023, China.
2 Department of Biological Sciences, National University of Singapore, 117543, Singapore.
Keywords:
target, mechanism of action, activation, heme, artemisinin, activity-based probe, chemical proteomics, malaria, artemisinin resistance.
Corresponding Author(s):
Conflict of interest statement:
The authors declare that no competing interest exists.
Please cite this article as:
Jigang Wang and Qingsong Lin (2016). Chemical proteomics approach reveals the direct targets and the heme-dependent activation mechanism of artemisinin in Plasmodium falciparum using an activity-based artemisinin probe. Microbial Cell 3(5):230-231. doi: 10.15698/mic2016.05.503
© 2016 Wang and Lin. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.
Abstract:
Artemisinin and its analogues are currently the most effective anti-malarial drugs. The activation of artemisinin requires the cleavage of the endoperoxide bridge in the presence of iron sources. Once activated, artemisinins attack macromolecules through alkylation and propagate a series of damages, leading to parasite death. Even though several parasite proteins have been reported as artemisinin targets, the exact mechanism of action (MOA) of artemisinin is still controversial and its high potency and specificity against the malaria parasite could not be fully accounted for. Recently, we have developed an unbiased chemical proteomics approach to directly probe the MOA of artemisinin in P. falciparum. We synthesized an activity-based artemisinin probe with an alkyne tag, which can be coupled with biotin through click chemistry. This enabled selective purification and identification of 124 protein targets of artemisinin. Many of these targets are critical for the parasite survival. In vitro assays confirmed the specific artemisinin binding and inhibition of selected targets. We thus postulated that artemisinin kills the parasite through disrupting its biochemical landscape. In addition, we showed that artemisinin activation requires heme, rather than free ferrous iron, by monitoring the extent of protein binding using a fluorescent dye coupled with the alkyne-tagged artemisinin. The extremely high level of heme released from the hemoglobin digestion by the parasite makes artemisinin exceptionally potent against late-stage parasites (trophozoite and schizont stages) compared to parasites at early ring stage, which have low level of heme, possibly derived from endogenous synthesis. Such a unique activation mechanism also confers artemisinin with extremely high specificity against the parasites, while the healthy red blood cells are unaffected. Our results provide a sound explanation of the MOA of artemisinin and its specificity against malaria parasites, which may benefit the optimization of treatment strategies and the battle against the emerging drug resistance.