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

PLoS Pathog. 2021 Oct 6;17(10):e1009969. doi: 10.1371/journal.ppat.1009969. eCollection 2021 Oct.


The pathology associated with malaria infection is largely due to the ability of infected human RBCs 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. ATPase assays on recombinant protein verify a functional interaction between PFA66 and residual host cell HSP70. Taken together, our data reveal a role for PFA66 in host cell modification, strongly implicate human HSP70s as being essential in this process and uncover a new KAHRP-independent molecular factor required for correct knob biogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • HSP70 Heat-Shock Proteins / metabolism*
  • Host-Parasite Interactions / physiology*
  • Humans
  • Malaria, Falciparum / metabolism*
  • Malaria, Falciparum / parasitology
  • Malaria, Falciparum / pathology
  • Plasmodium falciparum / metabolism
  • Plasmodium falciparum / pathogenicity*
  • Protozoan Proteins / metabolism*
  • Virulence


  • HSP70 Heat-Shock Proteins
  • Protozoan Proteins

Grant support

This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research foundation, grant 351262938 and 391524768 to JMP and 462625623 (MA1278/10-1) to MPM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.