Biology subjects

Guttery, D. S.

Publications and source records attributed to Guttery, D. S..

8 recordsLinked to original sources

bioRxiv2026

Plasmodium rootlet SFA1 coordinates cell replication, apical polarity and cytoskeletal organisation during sexual development

Rootlet fibres are evolutionarily conserved cytoskeletal structures involved in basal body positioning and cytoskeletal organisation in diverse eukaryotes. Plasmodium spps, undergo complex developmental transitions that require precise coordination of cell polarity, cytoskeletal remodelling and nuclear division. In Plasmodium striated fibre assemblin1 (SFA1) and SFA2 have been implicated in linking the centriolar plaque to nascent apical poles during schizogony and sporogony. However, their role in sexual development is unclear. Here we show SFA1 is absent from the male basal body but is present in female gametocytes, where it marks the polarity initiation site during zygote-to-ookinete differentiation. We also identify associations between SFA1, SFA2 and pellicle-associated proteins. Loss of sfa1 disrupts apical polarity, pellicle organisation and subpellicular microtubules, producing abnormal immotile ookinetes and affecting further sporozoite development, leading to complete loss of parasite transmission. Together, these findings support an important role for SFA1 in organising the cytoskeletal architecture required for malaria transmission.

cell biology↗

bioRxiv2026

Plasmodium Protein Kinase 2 is required for ookinete to oocyst transition, and parasite transmission by the mosquito.

Plasmodium spp., the parasites that are the causative agents of malaria, encode a repertoire of divergent protein kinases that coordinate essential processes including cell division and host cell invasion, yet the functions of many kinases are poorly defined. Plasmodium Protein Kinase 2 (PK2) is essential for asexual blood-stage proliferation and has been implicated in P. falciparum merozoite invasion of red blood cells. However, its role in the sexual stages of the Plasmodium life cycle responsible for transmission is unknown. Here, using live cell imaging, functional analyses, ultrastructure microscopy and phosphoproteomics, we demonstrate that PK2 has a significant role in the Plasmodium berghei life cycle in the mosquito. We show that PK2 is expressed in merozoites, ookinetes and sporozoites - the invasive stages of the parasite life cycle. A conditional knockdown approach revealed that PK2 is required for the ookinete to oocyst transition in the mosquito midgut, potentially associated with altered microneme positioning. Using haemocoel injection to bypass the midgut barrier revealed that PK2 is also required for sporozoite development after midgut invasion. Following PK2 knockdown, global proteome abundance was largely unaffected at 24 h post activation, whereas phosphoproteomics identified changes in phosphorylation of proteins linked to midgut traversal, parasite architecture, and gene regulation. These studies provide insight into the importance of PK2 function in Plasmodium sexual stages and parasite transmission through the mosquito, highlighting its essential function during the three invasive stages of the parasites life cycle.

microbiology↗

bioRxiv2025

A divergent Plasmodium NEK4 acts as a key regulator driving the early events of meiosis

Meiosis is a conserved yet evolutionarily varied process underpinning sexual reproduction in eukaryotes. In the malaria parasite Plasmodium, meiosis is unconventional: it occurs immediately after fertilisation (post-zygotic) and must be coordinated with the transformation of the zygote into a motile ookinete. The mechanisms synchronising these meiotic and morphogenetic programmes remain unknown. Here, we identify the Plasmodium berghei NIMA-related kinase NEK4 as a key regulator that couples meiotic initiation with zygote morphogenesis. Using ultrastructure expansion microscopy, we show that NEK4 accumulates at the microtubule-organising centre (MTOC) and the apical polar complex (APC) shortly after fertilisation, preceding the assembly of perinuclear and cortical microtubules. We reveal that Plasmodium zygotes undergo MTOC-associated nuclear migration, analogous to the meiotic nuclear movement in fission yeast. Deletion of the Pbnek4 gene results in complete developmental arrest: MTOC duplication and microtubule formation are blocked, chromatin remains uncondensed, and nuclear migration and cell polarity fail to establish. Transcriptomic and phosphoproteomic analyses reveal that absence of NEK4 causes a collapse in transcriptional and phosphoregulatory networks governing meiosis and cytoskeletal organisation, leading to reduced expression and phosphorylation of important players, including HOP1, REC8, and AP2-O. These findings establish NEK4 as a key regulator driving meiotic entry and zygote maturation.

microbiology↗

bioRxiv2025

Plasmodium ARK1 regulates spindle formation during atypical mitosis and forms a divergent chromosomal passenger complex

Mitosis in Plasmodium spp., the causative agent of malaria, is fundamentally different from model eukaryotes, proceeding via a bipartite microtubule organising centre (MTOC) and lacking canonical regulators such as Polo kinases. During schizogony, asynchronous nuclear replication produces a multinucleate schizont, while rapid male gametogony generates an octaploid nucleus before gamete formation. Here, we identify Aurora-related kinase 1 (ARK1) as a key component of inner MTOC and spindle formation, controlling kinetochore dynamics and driving mitotic progression. Conditional ARK1 depletion disrupts spindle biogenesis, kinetochore segregation, karyokinesis and cytokinesis in both stages, and affects parasite transmission. Interactome analysis shows that ARK1 forms the catalytic core of a non-canonical chromosomal passenger complex (CPC) containing two highly divergent inner centromere proteins (INCENPs), which we term INCENP-A and INCENP-B, and lacking the canonical chromatin-targeting subunits Survivin and Borealin. Comparative genomics suggests that apicomplexan INCENPs arose through recurrent lineage-specific duplications, reflecting an evolutionary rewiring of CPC architecture in this eukaryotic lineage. Together, these findings reveal key adaptations in Plasmodium mitosis involving ARK1 and its INCENP scaffolds, and identify the ARK1-INCENP interface as a potential multistage target for antimalarial intervention.

microbiology↗

bioRxiv2024

Divergent Plasmodium protein kinases drive MTOC, kinetochore and axoneme organisation in male gametogenesis

Sexual development and male gamete formation of the malaria parasite in the mosquito midgut is governed by rapid endomitosis in the activated male gametocyte. This process is highly regulated by protein phosphorylation, specifically by three divergent male-specific protein kinases (PKs): CDPK4, SRPK1 and MAP2. Here, we localise each PK during rapid male gamete formation using live-cell imaging, identify their putative substrates by immunoprecipitation, and determine the morphological consequences of their absence using ultrastructure expansion and transmission electron microscopy. Each PK has a distinct location in either the nuclear or cytoplasmic compartment. Protein interaction studies revealed that CDPK4 and MAP2 interact with key drivers of rapid DNA replication, while SRPK1 is involved in RNA translation. The absence of each PK results in severe defects in either microtubule organising centre (MTOC) organisation, kinetochore segregation or axoneme formation. This study reveals the crucial role of these PKs during endomitosis in formation of the flagellated male gamete and uncovers some of their potential substrates that drive this process. Summary blurbThis study reveals how Plasmodium kinases regulate MTOC, axoneme and kinetochore organisation in male gametogenesis, providing key insights into potential targets for malaria transmission control.

microbiology↗

bioRxiv2021

Protein Phosphatase 1 regulates atypical chromosome segregation and cell polarity during mitotic and meiotic division in Plasmodium sexual stages

PP1 is a conserved eukaryotic serine/threonine phosphatase that regulates many aspects of mitosis and meiosis, often working in concert with other phosphatases, such as CDC14 and CDC25. The proliferative stages of the malaria parasite life cycle include sexual development within the mosquito vector, with male gamete formation characterized by an atypical rapid mitosis, consisting of three rounds of DNA synthesis, successive spindle formation with clustered kinetochores, and a meiotic stage during zygote to ookinete development following fertilization. It is unclear how PP1 is involved in these unusual processes. Using real-time live-cell and ultrastructural imaging, conditional gene knockdown, RNA-seq and proteomic approaches, we show that Plasmodium PP1 is implicated in both mitotic exit and, potentially, establishing cell polarity during zygote development in the mosquito midgut, suggesting that small molecule inhibitors of PP1 should be explored for blocking parasite transmission.

cell biology↗

bioRxiv2020

A 3-hydroxyacyl-CoA dehydratase (DEH) involved in very long chain fatty acid synthesis is crucial for oocyst mitotic division but not cell size during parasite transmission in Plasmodium

Cells use fatty acids (FAs) for membrane biosynthesis, energy storage and the generation of signaling molecules. 3-hydroxyacyl-CoA dehydratase - DEH - is a key component of very long chain FA (VLCFA) synthesis. Here, we further characterized in-depth the location and function of DEH, applying in silico analysis, live cell imaging, reverse genetics and ultrastructure analysis using the mouse malaria model Plasmodium berghei. DEH is evolutionarily conserved across eukaryotes, with a single DEH in Plasmodium spp. and up to three orthologs in the other eukaryotes studied. DEH-GFP live-cell imaging showed strong GFP fluorescence throughout the life-cycle, with areas of localized expression in the cytoplasm and a circular ring pattern around the nucleus that colocalized with ER markers. {Delta}deh mutants showed a small but significant reduction in oocyst size compared to WT controls from day 10 post-infection onwards and endomitotic cell division and sporogony were completely ablated, blocking parasite transmission from mosquito to vertebrate host. Ultrastructure analysis confirmed degeneration of {Delta}deh oocysts, and a complete lack of sporozoite budding. Overall, DEH is evolutionarily conserved, localizes to the ER and plays a crucial role in sporogony.

cell biology↗

bioRxiv2019

Real-time dynamics of Plasmodium NDC80 as a marker for the kinetochore during atypical mitosis and meiosis

Eukaryotic cell proliferation requires chromosome replication and precise segregation to ensure daughter cells have identical genomic copies. The genus Plasmodium, the causative agent of malaria, displays remarkable aspects of nuclear division throughout its lifecycle to meet some peculiar and unique challenges of DNA replication and chromosome segregation. The parasite undergoes atypical endomitosis and endoreduplication with an intact nuclear membrane and intranuclear mitotic spindle. To understand these diverse modes of Plasmodium cell division, we have studied the behaviour and composition of the outer kinetochore NDC80 complex, a key part of the mitotic apparatus that attaches the centromere of chromosomes to microtubules of the mitotic spindle. Using NDC80-GFP live-cell imaging in Plasmodium berghei we observe dynamic spatiotemporal changes during proliferation, including highly unusual kinetochore arrangements during sexual stages. We identify a very divergent candidate for the SPC24 subunit of the NDC80 complex, previously thought to be missing in Plasmodium, which completes a canonical, albeit unusual, NDC80 complex structure. Altogether, our studies reveal the kinetochore as an ideal tool to investigate the non-canonical modes of chromosome segregation and cell division in Plasmodium. Summary StatementThe dynamic localization of kinetochore marker NDC80 protein complex during proliferative stages of the malaria parasite life cycle reveals unique modes of chromosome segregation.

cell biology↗