Super resolution: a closer look at the Plasmodium falciparum virulence complex

Looker O, Blanch A, McMillan P, Liu B, Dixon M and Tilley L

Department of Biochemistry & Molecular Biology, The University of Melbourne, Bio21 Molecular Science and Biotechnology Institute, Victoria 3010.

After invading the human red blood cell (RBC), Plasmodium falciparum modifies the host cell surface by exporting proteins to the RBC periphery. The physical properties of the RBC are altered and parasite derived structures called knobs arrive at the cell periphery where they are anchored to the RBC membrane skeleton. These knobs are comprised mainly of the Knob-Associated Histidine Rich Protein (KAHRP), which acts as a scaffold for the presentation of the major virulence protein, P. falciparumErythrocyte Membrane Protein 1 (PfEMP1), through the membrane. A method has been developed for exposing the inner-surface of the infected RBC membrane allowing for the organisation of the RBC membrane skeleton to be visualised by scanning electron microscopy and for protein location to be examined using super resolution localisation microscopy. This has allowed us to visualise knob assembly at the RBC membrane skeleton. In a major advance, we have combined these two imaging modalities in a CLEM (correlative light and electron microscopy) based approach to investigate membrane remodelling and virulence complex assembly. The development of CLEM techniques is allowing further investigation into how RBC membrane skeleton remodelling facilitates knob formation and how PfEMP1 arrives at the knobs to drive parasite virulence. Through combining multiple imaging modalities with cellular biology and biophysical measurements we aim to understand the remodelling events that underpin parasite virulence.