Malaria remains one of the most devastating parasitic diseases in the world with the vast majority of deaths caused by Plasmodium falciparum. The pathology of the disease results exclusively from the blood-stage of the infection during which parasites invade and multiply within host erythrocytes. To establish this intracellular niche, P. falciparum imposes striking modifications to the erythrocyte through export of effector proteins but the export mechanism is poorly understood and the effector functions essential to parasite survival remain largely unknown. Export into the red blood cell requires crossing a vacuole membrane surrounding the parasite, a translocation event that depends upon the Plasmodium translocon of exported proteins (PTEX). In a recent paper, the candidate showed that inactivation of heat shock protein 101 (HSP101), a AAA+ ATPase component of PTEX, results in a complete block in protein export and parasite death. Related AAA+ proteins can unfold and directionally thread substrates through a central channel, suggesting HSP101 may drive recognition of effector proteins and power the translocation process. The proposed career development plan aims to dissect the role of HSP101/PTEX in export and to identify key exported effectors that enable the parasite to survive within the erythrocyte.
Specific Aim 1 seeks to understand the substrate recognition and catalytic properties of recombinant HSP101 and to dissect the role of HSP101 in protein export within intact parasites.
Specific Aim 2 will use genetic and proteomic approaches to define the function of additional PTEX components and a cross-linking mass spectrometry approach to map the architecture of the complex.
Specific Aim 3 will analyze the function of exported effectors implicated in parasite survival within the erythrocyte using forward and reverse genetics as well as proteomic approaches. PTEX is an exciting new drug target and the proposed experiments will reveal key mechanistic information about the role of this export machinery as a necessary basis for rational drug design. Furthermore, identification of key exported proteins with roles in parasite survival may provide needed additional therapeutic targets. Collectively, this work will further our understanding of how the malaria parasite subverts its erythrocyte host cell and support development of new tools for control of malaria disease. The experience and research tools acquired in the process will propel the candidate into an established career as an independent investigator.

Public Health Relevance

Malaria is a devastating parasitic disease that results in ~600,000 annual deaths, most of which are caused by Plasmodium falciparum. To survive and evade host defenses, P. falciparum exports hundreds of effector proteins into the host red blood cell, an essential process that may be targeted to develop new therapeutics. The goal of this proposal is to determine how a parasite translocon called PTEX recognizes these exported proteins and transports them into the host cell and to identify key exported proteins that are necessary to modify the host cell for parasite survival.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Career Transition Award (K99)
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Special Emphasis Panel (MTI (MA))
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Klauzinska, Malgorzata
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Washington University
Internal Medicine/Medicine
Schools of Medicine
Saint Louis
United States
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Garten, Matthias; Nasamu, Armiyaw S; Niles, Jacquin C et al. (2018) EXP2 is a nutrient-permeable channel in the vacuolar membrane of Plasmodium and is essential for protein export via PTEX. Nat Microbiol 3:1090-1098
Glushakova, Svetlana; Beck, Josh R; Garten, Matthias et al. (2018) Rounding precedes rupture and breakdown of vacuolar membranes minutes before malaria parasite egress from erythrocytes. Cell Microbiol 20:e12868
Glushakova, Svetlana; Busse, Brad L; Garten, Matthias et al. (2017) Exploitation of a newly-identified entry pathway into the malaria parasite-infected erythrocyte to inhibit parasite egress. Sci Rep 7:12250
Nasamu, Armiyaw S; Glushakova, Svetlana; Russo, Ilaria et al. (2017) Plasmepsins IX and X are essential and druggable mediators of malaria parasite egress and invasion. Science 358:518-522
Spillman, Natalie J; Beck, Josh R; Ganesan, Suresh M et al. (2017) The chaperonin TRiC forms an oligomeric complex in the malaria parasite cytosol. Cell Microbiol 19: