Biology subjects

Kidner, R. Q.

Publications and source records attributed to Kidner, R. Q..

4 recordsLinked to original sources

bioRxiv2025

Structure-Based Optimization of Pathogen Signal Sequences for Enhanced Antigen Expression in Humans for Vaccine Designs

Signal peptides (SPs) are short amino acid sequences found at the N-terminus of nascent polypeptides, which serve critical roles in trafficking, folding, and post-translational processing of mature proteins. Many sequence-based computational methods have been developed to predict and design optimal SPs for protein secretion in human cells. In this work, we introduce a structure-based workflow for identifying SPs and their regions, aiming to optimize SPs for protein secretion in human cells. Structural modeling of the SPs in complex with human signal recognition particle 54 kDa (SRP54), combined with hydrophobicity plots of the SPs and identification of the cleavage motif, can be used to detect SPs and SP regions. Afterwards, LigandMPNN is applied to redesign the SPs based on their structural complexes with SRP54. We employ our workflow to optimize the bacterial Yersinia pestis F1 SP, Lassa virus glycoprotein (GP) SP, and Venezuelan equine encephalitis virus (VEEV) E3 envelope protein for protein secretion in human cells to serve as vaccine candidates. By comparing the redesigned SPs with the original SPs, we propose that the binding affinity of SPs to SRP54 serve as the most important molecular determinant in the activity of the SPs. Notably, our experiments confirm that the structurally optimized SPs can express the Y. pestis F1 protein, Lassa GP, and VEEV GP in human cells. Overall, we demonstrate that structural modeling can serve as a valuable tool to predict the SPs and SP regions for vaccine antigens, predict whether the SPs can express mature proteins in humans, and optimize the SPs for the expression of mature proteins in humans.

biophysics↗

bioRxiv2024

Exogenous lipid vesicles induce endocytosis-mediated cellular aggregation in a close unicellular relative of animals

Capsaspora owczarzaki is a protozoan that may both reveal aspects of animal evolution and also curtail the spread of schistosomiasis, a neglected tropical disease. Capsaspora exhibits a chemically regulated aggregative behavior that resembles cellular aggregation in some animals. This behavior may have played a key role in the evolution of animal multicellularity. Additionally, this aggregative behavior may be important for Capsasporas ability to colonize the intermediate host of parasitic schistosomes and potentially prevent the spread of schistosomiasis. Both applications demand elucidation of the molecular mechanism of Capsaspora aggregation. Toward this goal, we first determined the necessary chemical properties of lipid cues that activate aggregation. We found that a wide range of abundant zwitterionic lipids induced aggregation, revealing that the aggregative behavior could be activated by diverse lipid-rich conditions. Furthermore, we demonstrated that aggregation in Capsaspora requires clathrin-mediated endocytosis, highlighting the potential significance of endocytosis-linked cellular signaling in recent animal ancestors. Finally, we found that aggregation was initiated by post-translational activation of cell-cell adhesion--not transcriptional regulation of cellular adhesion machinery. Our findings illuminate the chemical, molecular and cellular mechanisms that regulate Capsaspora aggregative behavior--with implications for the evolution of animal multicellularity and the transmission of parasites.

biochemistry↗

bioRxiv2024

Host lipids regulate multicellular behavior of a predator of a human pathogen

As symbionts of animals, microbial eukaryotes benefit and harm their hosts in myriad ways. A model microeukaryote (Capsaspora owczarzaki) is a symbiont of Biomphalaria glabrata snails and may prevent transmission of parasitic schistosomes from snails to humans. However, it is unclear which host factors determine Capsasporas ability to colonize snails. Here, we discovered that Capsaspora forms multicellular aggregates when exposed to snail hemolymph. We identified a molecular cue for aggregation: a hemolymph-derived phosphatidylcholine, which becomes elevated in schistosome-infected snails. Therefore, Capsaspora aggregation may be a response to the physiological state of its host, and it may determine its ability to colonize snails and exclude parasitic schistosomes. Furthermore, Capsaspora is an evolutionary model organism whose aggregation may be ancestral to animals. This discovery, that a prevalent lipid induces Capsaspora multicellularity, suggests that this aggregation phenotype may be ancient. Additionally, the specific lipid will be a useful tool for further aggregation studies.

biochemistry↗

bioRxiv2022

Chemical factors induce aggregative multicellularity in a close unicellular relative of animals

Regulated cellular aggregation is an essential process for development and healing in many animal tissues. In some animals and a few distantly related unicellular species, cellular aggregation is regulated by diffusible chemical cues. However, it is unclear whether regulated cellular aggregation was part of the life cycles of the first multicellular animals and/or their unicellular ancestors. To fill this gap, we investigated the triggers of cellular aggregation in one of animals closest unicellular living relatives - the filasterean Capsaspora owczarzaki. We discovered that Capsaspora aggregation is induced by chemical cues, as observed in some of the earliest branching animals and other unicellular species. Specifically, we found that calcium ions and lipids present in lipoproteins function together to induce aggregation of viable Capsaspora cells. We also found that this multicellular stage is reversible, as depletion of the cues triggers disaggregation, which can be overcome upon re-induction. Our finding demonstrates that chemically regulated aggregation is important across diverse members of the holozoan clade. Therefore, this phenotype was plausibly integral to the life cycles of the unicellular ancestors of animals.

biochemistry↗