A recombinant rotavirus harboring a spike protein with a heterologous peptide reveals a novel role of VP4 in viroplasm stability

Papa, G.; Vetter, J.; Seyffert, M.; Gunasekera, K.; De Lorenzo, G.; Wiesendanger, M.; Schraner, E. M.; Reymond, J.-L.; Fraefel, C.; Burrone, O. R.; Eichwald, C.

doi:10.1101/2021.05.13.444118

bioRxiv · 10.1101/2021.05.13.444118

A recombinant rotavirus harboring a spike protein with a heterologous peptide reveals a novel role of VP4 in viroplasm stability

Papa, G.·Vetter, J.·Seyffert, M.·Gunasekera, K.·De Lorenzo, G.·Wiesendanger, M.·Schraner, E. M.·Reymond, J.-L.·Fraefel, C.·Burrone, O. R.·Eichwald, C.

View original source ↗Export metadata ↓

Abstract

The rotavirus (RV) VP4 spike protrudes as a trimeric structure from the five-fold axes of the virion triple-layer. Infectious RV particles need to be proteolytically cleaved in VP4 into two subunits, VP8* and VP5*, constituting both the distal part and central body of the virus spike. Modification of VP4 has been challenging as it is involved in biological process including the interaction with sialic acid and integrins, cell tropism and hemagglutinin activity. Here, we engineered a loop at position K145-G150 in the lectin domain of the VP8* subunit to harbor a small biotin acceptor peptide (BAP) tag and rescued viable viral particles using RV reverse genetics system. This rRV/VP4-BAP internalizes, replicates, and generates virus progeny, demonstrating that the VP4 spike of RV particles can be genetically manipulated by the incorporation of at least 15 exogenous amino acids. Although, VP4-BAP had a similar distribution as VP4 in infected cells by localizing in the cytoskeleton and surrounding viroplasms. However, compared to wild-type RV, rRV/VP4-BAP featured a reduced replication fitness and impaired viroplasm stability. Upon treatment of viroplasms with 1,6-hexanediol, a drug disrupting liquid-liquid phase-separated condensates, the kinetic of rRV/VP4-BAP viroplasm recovery was delayed, and their size and numbers reduced when compared to viroplasms of wild type RV. Moreover, siRNA silencing of VP4 expression in RV strain SA11 showed similar recovery patterns as rRV/VP4-BAP, revealing a novel function of VP4 in viroplasm stability. IMPORTANCEThe rotavirus (RV) spike protein, VP4, has a relevant role in several steps involving virion internalization. The strategic position of VP4 in the virion resulted in a challenge for the addition of an exogenous peptide producing infectious particles. The identification of a specific loop in position K145-G150 in the VP8* subunit of VP4 allowed the rescue by RV reverse genetics of a recombinant RV harboring VP4 containing a 15 amino acids tag. This study demonstrates this recombinant virus has similar replication properties as a wild-type virus. Moreover, we also discovered that VP4 is necessary for the assembly and stabilization of the cytosolic replication compartments, the viroplasms, demonstrating a novel role of this protein in the RV life cycle.

Explore related subjects

microbiology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Papa, G., Vetter, J., Seyffert, M., Gunasekera, K., De Lorenzo, G., Wiesendanger, M., Schraner, E. M., Reymond, J.-L., Fraefel, C., Burrone, O. R., Eichwald, C.. 2021-05-14. A recombinant rotavirus harboring a spike protein with a heterologous peptide reveals a novel role of VP4 in viroplasm stability. https://doi.org/10.1101/2021.05.13.444118

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Microbially conjugated bile acids differentially affect the lifecycle and pathogenesis of Clostridioides difficile

Clostridioides difficile is a Gram-positive bacterium that causes C. difficile infection (CDI). In healthy adults, it has been proposed that the gut microbiota provides colonization resistance against C. difficile by competition through nutrient limitation and antagonism through secondary bile acid metabolism, the latter of which is mediated by the deconjugation of host-derived bile acids with bacterial bile salt hydrolases (BSH). Recently, BSHs have also shown an ability to reconjugate non-canonical (i.e., not glycine or taurine) amino acids to sterol cores, resulting in novel microbially conjugated bile acids (MCBAs). MCBAs have been associated with the resolution of recurrent CDI, though the mechanism underlying these effects are not well understood. To address this gap, we synthesized 36 MCBAs with nine amino acids (cysteine, isoleucine, leucine, phenylalanine, proline, serine, tryptophan, tyrosine, and valine) conjugated to the primary and secondary bile acids found in the human gut (CA, DCA, CDCA, and LCA) and tested their impact on various stages of C. difficiles lifecycle including bacterial outgrowth, membrane integrity, sporulation, and toxin activity. We show that BSH-mediated amidation of bile acid sterol cores can either increase or decrease inhibitory effects on C. difficile in an amino acid-dependent manner. For example, serine MCBAs enhanced C. difficiles ability to grow in otherwise inhibitory bile acid concentrations, increased spore production, and elevated toxin activity. Tryptophan MCBAs increased inhibition. By demonstrating these variable effects, our work clarifies the molecular determinants of MCBA activity and highlights specific MCBAs as promising targets for the development of C. difficile microbial-based therapeutics.

microbiology↗

bioRxiv2026

Magnetic organelle gene clusters enable bacterial growth and ATP homeostasis under oxidizing conditions

Biological organisms can produce magnetic nanoparticles made of magnetite to detect the Earth's magnetic field for orientation. The evolutionary mechanisms that led to the acquisition of this capacity remain unknown. The most ancient organisms known to perform magnetic orientation are magnetotactic bacteria. Under tight genetic control, they produce chains of magnetite nanoparticles in dedicated organelles to allow efficient navigation in aquatic environments containing molecular oxygen. Yet, these bacteria have been proposed to emerge before molecular oxygen became abundant on Earth, at a time when this navigation system could not have served its current function. Here, we show that gene clusters responsible of magnetite formation and organization enable resistance against hydrogen peroxide, a toxic oxygen-derived compound that was produced during the early stages of Earth's oxygenation when iron oxidation consumed molecular oxygen. Characterization of the nanoparticle's oxidation state supported the involvement of magnetite in resistance to hydrogen peroxide-induced oxidative stress. These findings are compatible with an early emergence of magnetotactic bacteria, before natural waters became oxygenated. We propose a conceptual framework to explain the origin of magnetic orientation in bacteria, and offer tools to identify the initiation of Earth's oxygenation in a time-resolved manner.

microbiology↗

bioRxiv2026

Identification and characterization of new P. aeruginosa phages using a surface receptor platform

Bacteriophages are of increasing interest for their potential use as alternatives to antibiotics for treating drug-resistant infections. Phage steering, specifically receptor-based steering, involves use of phages that bias the development of resistance in bacteria towards phenotypes such as reduced fitness. Phage therapy typically involves administering cocktails of phages with different targets to reduce the likelihood of resistance emerging. To ensure effective steering and cocktail design, there is a need to identify the receptors used by phages of interest, and to isolate phages that use diverse receptors. Here we describe a SURFAce Receptor (SURFAR) platform consisting of a set of defined Pseudomonas aeruginosa strains and mutants for rapid characterization of phage receptors. This platform can also be used to enrich for and isolate diverse phages from environmental samples, yielding novel phage genomes from wastewater. Using the SURFAR platform, two new phages were isolated and characterized: Dalewood, which targets both flagella and the conserved LPS outer core, and Bowman, a biofilm targeting phage capable of supressing growth of a subset of carbapenem-resistant clinical isolates. This tool helps to standardize the laborious but important task of phage receptor characterization, with the goal of expanding the known repertoire of P. aeruginosa phage receptors and phages.

microbiology↗