Biology subjects

Przyborski, J. M.

Publications and source records attributed to Przyborski, J. M..

4 recordsLinked to original sources

bioRxiv2024

A systematic targeted genetic screen identifies proteins involved in cytoadherence of the malaria parasite P. falciparum.

Immediately after invading their chosen host cell, the mature human erythrocyte, malaria parasites begin to export an array of proteins to this compartment, where they initiate processes that are prerequisite for parasite survival and propagation, including nutrient import and immune evasion. One consequence of these activities is the emergence of novel adhesive phenotypes that can lead directly to pathology in the human host. To identify parasite proteins involved in this process we used modern genetic tools to target genes encoding 15 exported parasite proteins, selected by an in-silico workflow. This resulted in 4 genetically modified parasite lines that were then characterised in detail. Of these lines, 3 could be shown to have aberrations in adhesion, and of these 1 appears to have a block in the transport and/or correct folding of the major surface adhesin PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1). Our data expand the known factors involved in this important process, and once again highlight the complexity of this phenomenon.

cell biology↗

bioRxiv2024

Mitochondrial ATP synthesis is essential for efficient gametogenesis in Plasmodium falciparum

Interrupting parasite transmission from humans to mosquitoes is vital for malaria elimination and eradication. Plasmodium male and female gametocytes are the gatekeepers of human to mosquito transmission. Whilst dormant in the human host, their divergent roles during transmission become visually apparent soon after ingestion by the mosquito after rapid transformation into gametes - the males forming eight motile sperm-like cells that each aim to fertilise a single female gamete. Here we report that antibodies raised against PfLDH2 allow accurate identification of male gametocytes. Using this novel tool and functional mitochondrial labelling, we show that the male gametocyte mitochondrion is less active than that of female gametocytes. Rather than being a vestigial organelle discarded during male gametogenesis, we demonstrate that mitochondrial ATP synthesis is essential for male gametocytes to complete gametogenesis and inhibition leads to early arrest. Additionally, using a genetically encoded ratiometric sensor of ATP, we show that gametocytes can maintain cytoplasmic ATP homeostasis in the absence of mitochondrial respiration, indicating the essentiality of the gametocyte mitochondrion for transmission alone. Together, this reveals how gametocytes balance the conflicting energy demands of a dormant and active lifestyle and highlights the mitochondria as a rich source of transmission-blocking targets for future drug development.

microbiology↗

bioRxiv2023

Real-time measurements of ATP dynamics via ATeams in Plasmodium falciparum reveal drug-class-specific response patterns

Malaria tropica, caused by the parasite Plasmodium falciparum (P. falciparum) remains one of the greatest public health burdens for humankind. Due to its pivotal role in parasite survival, the energy metabolism of P. falciparum is an interesting target for drug design. To this end, analysis of the central metabolite ATP is of great interest. So far, only cell disruptive or intensiometric ATP assays have been available in this system, with various drawbacks for mechanistic interpretation, and partly inconsistent results. To address this, we have established fluorescent probes, based on FRET and known as ATeam, for use in blood stage parasites. ATeams are capable of measuring MgATP2- levels in a ratiometric manner, thereby facilitating in cellulo measurements of ATP dynamics in real-time using fluorescence microscopy and plate reader detection, and overcoming many of the obstacles of established ATP analysis methods. Additionally, we established a superfolder variant of the ratiometric pH sensor pHluorin (sfpHluorin) in P. falciparum to monitor pH homeostasis and control for pH fluctuations, which may affect ATeam measurements. We characterized recombinant ATeam and sfpHluorin protein in vitro and stably integrated the sensors into the genome of the P. falciparum NF54attB cell line. Using these new tools, we found distinct sensor response patterns caused by several different drug classes. Arylamino alcohols increased and redox-cyclers decreased ATP, doxycycline caused first-cycle cytosol alkalization, and 4-aminoquinolines caused aberrant proteolysis. Our results open up a completely new perspective on drugs mode of action with possible implications for target identification and drug development.

microbiology↗

bioRxiv2021

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

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.

cell biology↗