Co-chaperone involvement in knob biogenesis implicates host-derived chaperones in malaria virulence

• Published in: bioRxiv
• Main Authors: Diehl, Mathias, Weber, Sebastian, Cyrklaff, Marek, Sanchez, Cecilia P, Beretta, Carlo A, Roling, Lena, Simon, Caroline S, Guizetti, Julien, Mayer, Matthias P, Przyborski, Jude M
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 11.03.2021
• Subjects: Biosynthesis; Cell culture; Cell membranes; Chaperones; Cytology; Endothelial cells; Erythrocytes; Histidine; Hsp70 protein; Immunofluorescence; Malaria; Microscopy; Neomycin; Parasitophorous vacuole; Permeability; Phenotypes; Proteins; Scanning electron microscopy; Transmission electron microscopy; Virulence
• DOI: 10.1101/2021.03.11.434953

Abstract The pathology associated with malaria infection is largely due to the ability of infected human erythrocytes to adhere to a number of receptors on endothelial cells within tissues and organs. This phenomenon is driven by the export of parasite-encoded proteins to the host cell, the exact function of many of which is still unknown. Here we inactivate the function of one of these exported proteins, PFA66, a member of the J-domain protein family. Although parasites lacking this protein were still able to grow in cell culture, we observed severe defects in normal host cell modification, including aberrant morphology of surface knobs, disrupted presentation of the cytoadherence molecule PfEMP1, and a total lack of cytoadherence, despite the presence of the knob associated protein KAHRP. Complementation assays demonstrate that an intact J-domain is required for recovery to a wild-type phenotype and suggest that PFA66 functions in concert with a HSP70 to carry out host cell modification. Strikingly, this HSP70 is likely to be of host origin. Taken together, our data reveal a role for PFA66 in host cell modification, implicate human HSP70 as also being essential in this process, and uncover a KAHRP-independent mechanism for correct knob biogenesis. Our observations open up exciting new avenues for the development of new anti-malarials. Competing Interest Statement The authors have declared no competing interest. * Abbreviations SLI selection-linked integration (i)RBC (infected) red blood cell PV(M) parasitophorous vacuole (membrane) RBCM red blood cell membrane PPM parasite plasma membrane BSD blasticidin NEO neomycin KAHRP knob-associated histidine-rich protein SEM scanning electron microscopy TEM transmission electron microscopy (r)STED (rescue) stimulated emission depletion NPP new permeability pathways IFA immunofluorescence assay EQT equinatoxin CSA chondroitin-sulphate-A MC Maurer’s clefts