Biology subjects

Anaguano, D.

Publications and source records attributed to Anaguano, D..

3 recordsLinked to original sources

bioRxiv2024

Plasmodium RON11 triggers biogenesis of the merozoite rhoptry pair and is essential for erythrocyte invasion

Malaria is a global and deadly human disease caused by the apicomplexan parasites of the genus Plasmodium. Parasite proliferation within human red blood cells (RBC) is associated with the clinical manifestations of the disease. This asexual expansion within human RBCs, begins with the invasion of RBCs by P. falciparum, which is mediated by the secretion of effectors from two specialized club-shaped secretory organelles in merozoite-stage parasites known as rhoptries. We investigated the function of the Rhoptry Neck Protein 11 (RON11), which contains seven transmembrane domains and calcium-binding EF-hand domains. We generated conditional mutants of the P. falciparum RON11. Knockdown of RON11 inhibits parasite growth by preventing merozoite invasion. The loss of RON11 did not lead to any defects in processing of rhoptry proteins but instead led to a decrease in the amount of rhoptry proteins. We utilized ultrastructure expansion microscopy (U-ExM) to determine the effect of RON11 knockdown on rhoptry biogenesis. Surprisingly, in the absence of RON11, fully developed merozoites had only one rhoptry each. The single rhoptry in RON11 deficient merozoites were morphologically typical with a bulb and a neck oriented into the apical polar ring. Moreover, rhoptry proteins are trafficked accurately to the single rhoptry in RON11 deficient parasites. These data show that in the absence of RON11, the first rhoptry is generated during schizogony but upon the start of cytokinesis, the second rhoptry never forms. Interestingly, these single-rhoptry merozoites were able to attach to host RBCs but are unable to invade RBCs. Instead, RON11 deficient merozoites continue to engage with RBC for prolonged periods eventually resulting in echinocytosis, a result of secreting the contents from the single rhoptry into the RBC. Together, our data show that RON11 triggers the de novo biogenesis of the second rhoptry and functions in RBC invasion.

cell biology↗

bioRxiv2023

Atlas of Plasmodium falciparum intraerythrocytic development using expansion microscopy

Apicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample [~]4.5x. Here, we apply U-ExM to the human malaria parasite Plasmodium falciparum during the asexual blood stage of its lifecycle to understand how this parasite is organized in three-dimensions. Using a combination of dye-conjugated reagents and immunostaining, we have catalogued 13 different P. falciparum structures or organelles across the intraerythrocytic development of this parasite and made multiple observations about fundamental parasite cell biology. We describe that the outer centriolar plaque and its associated proteins anchor the nucleus to the parasite plasma membrane during mitosis. Furthermore, the rhoptries, Golgi, basal complex, and inner membrane complex, which form around this anchoring site while nuclei are still dividing, are concurrently segregated and maintain an association to the outer centriolar plaque until the start of segmentation. We also show that the mitochondrion and apicoplast undergo sequential fission events while maintaining an association with the outer centriolar plaque during cytokinesis. Collectively, this study represents the most detailed ultrastructural analysis of P. falciparum during its intraerythrocytic development to date, and sheds light on multiple poorly understood aspects of its organelle biogenesis and fundamental cell biology. IMPACT STATEMENTUsing ultrastructure-expansion microscopy we explore the fundamental cell biology of malaria parasites, providing new insights into processes including establishment of cell polarity and organelle fission.

cell biology↗

bioRxiv2022

RAPID, TIME-RESOLVED PROXIMITY LABELING BY SBP1 IDENTIFIES A PORIN DOMAIN PROTEIN AT THE MALARIA PARASITE PERIPHERY

The deadly human malaria-causing parasite, Plasmodium falciparum relies on its capacity to completely remodel its host red blood cell (RBC) through the export of hundreds of parasite proteins across several membranes to the RBC. Among these exported proteins are numerous membrane proteins that are inserted into the parasite plasma membrane (PPM) during their transport via the secretory pathway. It is not known how these exported membrane proteins are extracted from the PPM for export. To answer this question, we fused the exported membrane protein skeleton binding protein 1 (SBP1) with the rapid, efficient, and promiscuous biotin ligase known as TurboID (SBP1TbID). Our data show that the SBP1TbID fusion protein was exported efficiently to the host RBC and was able to rapidly biotinylate proteins at the host-parasite interface during its export as well as at its final destination in the host RBC. Using time-resolved proximity biotinylation and label-free quantitative proteomics, we identified early (pre-export) interactors and late (post-export) interactors of SBP1TbID. This led to the identification of 24 proteins that were 10-fold or more enriched in the pre-export time point compared to the post-export time point. Among these early interactors were two promising membrane-associated proteins, one of which has a predicted porin domain, that could potentially act as a translocon at the PPM for exported membrane proteins (Plasmodium translocon of exported membrane proteins or PTEM). Both proteins localize to the host-parasite interface during early stages of the intraerythrocytic cycle and conditional knockdown of these candidates show that they play essential roles in the asexual lifecycle of the parasite. Taken together, our data suggest that these two proteins may play a role in extracting membrane proteins from the PPM for export to the host RBC.

cell biology↗