The Day the Hemozoin Stood Still: Unraveling the Chaotic Tumbling of Nanoscale Crystals in Malaria Parasites

During red blood cell infection, malaria parasites digest copious amounts of hemoglobin and neutralize toxic heme by forming hemozoin crystals that twirl within the acidic food vacuole (FV). Crystal formation is a central component of parasite survival, but the motion and its origin are unstudied. This phenomenon presents a major gap in basic understanding of vacuolar function and parasite biology. In this study, we used image analysis methods to uncover the minimum environmental requirements to maintain crystal motion. To determine exact crystal trajectories, we used hypotonic swelling of the FV to increase the organellar volume and enable single particle tracking. We compared hemozoin dynamics to other simplified systems of Brownian motion and showed that the anomalous results cannot be reproduced. To investigate this motion more precisely, we developed a simulation approach to add complex factors of the FV environment and found that even the simulated environment could not account for crystal dynamics. Finally, we showed that hydrogen peroxide, which is generated at high concentrations within the FV, enhances crystal motion by over two-fold, as expected for metal-catalyzed H₂O₂ decomposition. Taken together, our results suggest a striking chemical reaction between reactive oxygen species and inert crystal faces, providing local point forces to maintain and stimulate hemozoin motion in the FV.