Biology subjects

Hauser, D.

Publications and source records attributed to Hauser, D..

7 recordsLinked to original sources

bioRxiv2026

Localization-dependent activation of the DEAD-box ATPase Vasa by eLOTUS domains

DEAD-box RNA helicases remodel RNA structures in many cellular pathways, yet how their activity is spatially controlled in cells remains poorly understood. The Drosophila germline helicase Vasa functions in ovaries only when localized to cytoplasmic granules, a process mediated by eLOTUS-domain proteins. Here, we define the mechanism by which eLOTUS domains activate Vasa. Biochemical analyses reveal that Vasa alone is largely inactive. eLOTUS domains bind the open conformation of Vasa and promote formation of the closed RNA- and ATP-bound state by accelerating RNA engagement. This stimulation requires a positively charged intrinsically disordered sequence within eLOTUS that increases RNA association. Mutations in this element abolish Vasa stimulation while preserving binding. We demonstrate that Vasa activation is essential in vivo. Together, these findings reveal a localization-dependent mechanism for regulating the DEAD-box helicase Vasa, in which enzymatic activity is gated by a spatially restricted cofactor.

biochemistry↗

bioRxiv2026

One and Done: A safe, adaptable single-cycle SARS-CoV-2 vaccine platform blocks XBB.1.5 infection and transmission

A next-generation SARS-CoV-2 vaccine must address the currently inadequate prevention of virus transmission, particularly against emerging variants of concern, a challenge that none of the licensed commercial vaccines fully meet. Effective control of respiratory pandemics necessitates vaccines that 1) can be rapidly adapted, 2) have high patient compliance with simple and non-invasive administration, and 3) block transmission in a virus challenge. We describe here the characterization of an updated single-cycle SARS-CoV-2 vaccine candidate (scVac), engineered as a replication-defective virus with targeted deletions of the E gene and ORF6 and ORF7a, along with a truncation of ORF3a. The candidate carries an Omicron XBB.1.5 Spike (scVacXBB), maintaining all essential antigenic properties. The vaccine demonstrated an excellent safety profile in K18-hACE2 transgenic mice, the most sensitive virulence model, with no clinical signs or adverse events observed. In the Syrian hamster model, potent systemic and mucosal immune responses were induced, along with a strong neutralizing antibody response. Notably, there was no virus transmission to co-housed naive animals, which outperforms a bivalent Omicron mRNA vaccine reference. Our results demonstrate that scVacXBB-induced immunity not only prevents disease but also effectively blocks transmission. Furthermore, the successful introduction of the XBB.1.5 Spike protein into the scVac platform demonstrates the pipelines ability to adapt quickly to any emerging variant. These findings highlight the potential of this single-cycle concept as a next-generation COVID-19 vaccine, offering robust protection with a strong safety profile.

immunology↗

bioRxiv2025

Atovaquone-venturicidin A combination is synergistic against Plasmodium falciparum

We report the synergistic interaction between the complex III inhibitor atovaquone and an ATP synthase inhibitor, venturicidin A, against Plasmodium falciparum. Our results suggest the simultaneous inhibition of the parasites primary and alternative pathways for generating the mitochondrial membrane potential to be responsible for this phenomenon, whereby the alternative pathway relies on ATP synthase running in reverse mode. We hypothesize that the synergistic interaction between atovaquone and proguanil could follow a similar mechanism.

microbiology↗

bioRxiv2025

Rieske Iron-Sulfur Cluster Proteins from an Anaerobic Ammonium Oxidizer Suggest Unusual Energetics in their Parent Rieske/cytochrome b complexes

Anaerobic ammonium-oxidizing (anammox) bacteria employ a unique, hydrazine-based pathway to obtain energy from nitrite and ammonium. These organisms express distinct Rieske/ cytochrome b complexes whose precise role in anammox metabolism remains unclear, but which has been proposed to include the generation of NAD(P)H. This would require energetics and structural features unusual for such complexes. Here we present crystal structures and electrochemical investigations of the Rieske subunits of two of these complexes from the anammox organism Kuenenia stuttgartiensis, Kuste4569 and Kustd1480. Both proteins display high redox potentials (>+300 mV), which can be in part explained by their crystal structures and which fit perfectly into the energetic scheme of the proposed NAD(P)H generation mechanism. Moreover, AlphaFold3 models of the parent complexes trace out a path for the electrons required for NAD(P) production, which includes a proposed, novel b-type heme in the membrane-bound part of the complex.

biochemistry↗

bioRxiv2024

Molecular insight into the network of Drosophila cytoplasmic piRNA pathway proteins through a combination of systematic interaction screening and structural prediction

piRNA-bound PIWI proteins mediate the silencing of transposons at both the transcriptional and post-transcriptional levels, processes that are critical for genome integrity and fertility in animals. While numerous additional proteins are known to be essential for piRNA biogenesis and function in Drosophila and other animals, their molecular and mechanistic functions have remained largely unknown. To improve our molecular understanding of the Drosophila piRNA pathway, we used a cell culture-based protein-protein interaction assay called ReLo to perform a systematic pairwise interaction screen involving 22 factors operating in the cytoplasm, including PIWI proteins, Tudor domain-containing proteins (TDRDs), RNA helicases, and mitochondrial surface proteins. Through additional ReLo interaction testing and structural modeling using AlphaFold-Multimer, we have characterized six protein complexes at the molecular and structural levels. We believe that the results of this screen and our methodological approach are likely to guide future research into the molecular mechanisms underlying piRNA biogenesis and function.

biochemistry↗

bioRxiv2023

Single-cycle SARS-CoV-2 vaccine elicits high protection and sterilizing immunity in hamsters

Vaccines have been central in ending the COVID-19 pandemic, but newly emerging SARS-CoV-2 variants increasingly escape first-generation vaccine protection. To fill this gap, live particle-based vaccines mimicking natural infection aim at protecting against a broader spectrum of virus variants. We designed "single-cycle SARS-CoV-2 viruses" (SCVs) that lack essential viral genes, possess superior immune-modulatory features and provide an excellent safety profile in the Syrian hamster model. Full protection of all intranasally vaccinated animals was achieved against an autologous challenge with SARS-CoV-2 virus using an Envelope-gene-deleted vaccine candidate. By deleting key immune-downregulating genes, sterilizing immunity was achieved with an advanced candidate without virus spread to contact animals. Hence, SCVs have the potential to induce a broad and durable protection against COVID-19 superior to a natural infection.

molecular biology↗

bioRxiv2023

Rapid cloning-free mutagenesis of new SARS-CoV-2 variants using a novel reverse genetics platform

Reverse genetic systems enable the engineering of RNA virus genomes and are instrumental in studying RNA virus biology. With the recent outbreak of the COVID-19 pandemic, already established methods were challenged by the large genome of SARS-CoV-2. Herein we present an elaborated strategy for the rapid and straightforward rescue of recombinant plus-stranded RNA viruses with high sequence fidelity, using the example of SARS-CoV-2. The strategy called CLEVER (CLoning-free and Exchangeable system for Virus Engineering and Rescue) is based on the intracellular recombination of transfected overlapping DNA fragments allowing the direct mutagenesis within the initial PCR-amplification step. Furthermore, by introducing a linker fragment - harboring all heterologous sequences - viral RNA can directly serve as a template for manipulating and rescuing recombinant mutant virus, without any cloning step. Overall, this strategy will facilitate recombinant SARS-CoV-2 rescue and accelerate its manipulation. Using our protocol, newly emerging variants can quickly be engineered to further elucidate their biology. To demonstrate its potential as a reverse genetics platform for plus-stranded RNA viruses, the protocol has been successfully applied for the cloning-free rescue of recombinant Chikungunya and Dengue virus.

molecular biology↗