Biology subjects

Kudulyte, A.

Publications and source records attributed to Kudulyte, A..

4 recordsLinked to original sources

bioRxiv2025

A genetically encoded marker for imaging membranes of Plasmodium

Fluorescence microscopy is a powerful tool to analyze subcellular architecture, and long-term live-cell imaging permits the analysis of the dynamics of intracellular structures. Applying this approach to the membranes of Plasmodium spp., the causative agent of malaria, yielded important insight. Fluorescent labelling of Plasmodiums plasma membrane via membrane-resident proteins has been described, but proteins, which broadly mark internal membranes are currently elusive. Alternatively, general membrane dyes can be employed to study membrane dynamics, however, we find that the membrane dye BODIPY TR Ceramide has adverse effects on cell viability during live-cell imaging. To overcome this limitation, we present FLUMMI (Fixed-and-Live-cell Universal Membrane Marker for Imaging), a 32-amino acid long peptide derived from P. falciparum PCNA1, which targets (fluorescent) protein tags to internal membranes for detection in live or fixed samples. Importantly, FLUMMI enables non-invasive, long-term live-cell imaging of internal membranes without affecting P. falciparum viability and is functional in blood stages of both, the human malaria parasite P. falciparum and the rodent-infecting parasite P. berghei, as well as in P. berghei mosquito stages. FLUMMI is also compatible with advanced techniques such as expansion microscopy. Together, our results establish FLUMMI as a versatile and non-toxic tool for membrane imaging in Plasmodium.

microbiology↗

bioRxiv2025

Competitive resource allocation drives asynchronous and rapid nuclear multiplication in the malaria parasite

The unicellular malaria parasite Plasmodium falciparum proliferates within the red blood cells of its human host, where it generates approximately 20 new parasites within an infection cycle of two days. Proliferation proceeds by nuclear divisions in a shared cytoplasm, followed by cellularization. In stark contrast to the highly synchronized nuclear division cycles in many eukaryotes, Plasmodium nuclear cycles desynchronize rapidly. Here, we elucidate the mechanism of desynchronization and study its impact on parasite fitness by combining live-cell imaging of DNA replication with biophysical modeling. We find that the standard model of independent nuclear cycles with transgenerational inheritance cannot account for the experimental data, and therefore desynchronization requires nuclear coupling. Competition for a limiting pool of a replication resource explains the data, provided that the resource is allocated sequentially to individual nuclei. Sequential allocation can be achieved by stable but reversible loading of a replication component to DNA, for example proliferating cell nuclear antigen (PCNA). Remarkably, the resultant asynchronous nuclear cycles accelerate parasite proliferation by minimizing idling times of resources. Indeed, we predict theoretically that this mechanism maximizes overall proliferation rate with limited resource availability. Thus, our findings identify nuclear cycle asynchrony as a resource-efficient means to achieve rapid proliferation.

biophysics↗

bioRxiv2023

The phenuivirus Toscana virus makes an atypical use of vacuolar acidity to enter host cells

Toscana virus is a major cause of arboviral disease in humans in the Mediterranean basin during summer. However, early virus-host cell interactions and entry mechanisms remain poorly characterized. Investigating iPSC-derived human neurons and cell lines, we found that virus binding to the cell surface was specific but inefficient, and 50% of bound virions were endocytosed within 10 min. Virions entered Rab5a+ early endosomes and, subsequently, Rab7a+ and LAMP-1+ late endosomal compartments. Penetration required intact late endosomes and occurred within 30 min following internalization. Virus entry relied on vacuolar acidification, with an optimal pH for viral membrane fusion at pH 5.5. The pH threshold increased to 5.8 with longer pre-exposure of virions to the slightly acidic pH in early endosomes. Strikingly, the particles remained infectious after entering late endosomes with a pH below the fusion threshold. Overall, our study establishes Toscana virus as a late-penetrating virus and reveals an atypical use of vacuolar acidity by this virus to enter host cells.

microbiology↗

bioRxiv2021

Asynchronous nuclear cycles in multinucleated Plasmodium falciparum enable rapid proliferation

Malaria-causing parasites proliferate within erythrocytes through schizogony, forming multinucleated stages before cellularization. Nuclear multiplication does not follow a strict geometric 2n progression and each proliferative cycle produces a heterogeneous number of progeny. Here, by tracking nuclei and DNA replication, we show that individual nuclei replicate their DNA at different times, despite residing in a shared cytoplasm. Extrapolating from experimental data using mathematical modeling, we demonstrate that a limiting factor must exist that slows down the nuclear multiplication rate. Indeed, our data show that temporally overlapping DNA replication events were significantly slower than partially or non-overlapping events. Our findings suggest an evolutionary pressure that selects for asynchronous DNA replication, balancing available resources with rapid pathogen proliferation.

microbiology↗