Biology subjects

Reymond, J.-L.

Publications and source records attributed to Reymond, J.-L..

5 recordsLinked to original sources

bioRxiv2026

Mechanistic basis of teichoic acid transport by a gatekeeper flippase

The cell wall is a complex structure that protects bacteria from environmental threats. Phosphocholine-containing teichoic acids are key cell wall biopolymers critical for host colonization, immune evasion, competence, and persistence in Streptococcus pneumoniae. The flippase TacF, a member of the multidrug/oligosaccharide-lipid/polysaccharide (MOP) superfamily, monitors the phosphocholine content of teichoic acids during transport, yet the underlying mechanism of this process remains unknown. We present a cryo-EM structure of S. pneumoniae TacF in lipid nanodiscs. In vivo complementation assays and molecular dynamics simulations reveal key residues involved in teichoic acid recognition and transport, while coevolutionary and conservation analyses delineate common mechanistic elements among MOP flippases, indicating a shared mechanism for polyprenyl-diphosphate-linked oligosaccharide lipid transport. Our findings provide mechanistic insights into an essential flippase involved in S. pneumoniae pathogenesis and a potential drug target.

biochemistry↗

bioRxiv2024

Leveraging machine learning to streamline the development of liposomal drug delivery systems

Drug delivery systems efficiently and safely administer therapeutic agents to specific body sites. Liposomes, spherical vesicles made of phospholipid bilayers, have become a powerful tool in this field, especially with the rise of microfluidic manufacturing during the COVID-19 pandemic. Despite its efficiency, microfluidic liposomal production poses challenges, often requiring laborious, optimization on a case-by-case basis. This is due to a lack of comprehensive understanding and robust methodologies, compounded by limited data on microfluidic production with varying lipids. Artificial intelligence offers promise in predicting lipid behaviour during microfluidic production, with the still unexploited potential of streamlining development. Herein we employ machine learning to predict critical quality attributes and process parameters for microfluidic-based liposome production. Validated models predict liposome formation, size, and production parameters, significantly advancing our understanding of lipid behaviour. Extensive model analysis enhanced interpretability and investigated underlying mechanisms, supporting the transition to microfluidic production. Unlocking the potential of machine learning in drug development can accelerate pharmaceutical innovation, making drug delivery systems more adaptable and accessible.

pharmacology and toxicology↗

bioRxiv2023

TurboID mapping reveals exportome of secreted intrinsically disordered proteins in the transforming parasite Theileria annulata

Theileria annulata is a tick-transmitted apicomplexan parasite that gained the unique ability among parasitic eukaryotes to transform its host cell, inducing a fatal cancer-like disease in cattle. Understanding the mechanistic interplay driving this transformation between the host cell and malignant Theileria species requires the identification of responsible parasite effector proteins. In this study, we used TurboID-based proximity labelling, which unbiasedly identified secreted effector proteins within host cell compartments. By fusing TurboID to nuclear export or localization signals, we biotinylated proteins in the vicinity of the ligase enzyme in the nucleus or cytoplasm of infected macrophages, followed by mass spectrometry analysis. Our approach revealed with high confidence nine nuclear and four cytosolic candidate effector proteins within the host cell compartments, eight of which had no orthologues in non-transforming T. orientalis. Strikingly, all eight of these proteins are predicted to be highly intrinsically disordered proteins (IDPs). We discovered a novel tandem arrayed protein family, Nuclear Intrinsically Disordered Proteins (NIDP) 1 - 4, featuring diverse functions predicted by conserved protein domains. Particularly, NIDP2 exhibited a biphasic host cell-cycle dependent localization, interacting with the EB1/CD2AP/CLASP1 parasite membrane complex during mitosis and the tumor suppressor Stromal Antigen 2 (STAG2), a cohesion complex subunit, in the host nucleus. In addition to STAG2, numerous NIDP2-associated host nuclear proteins implicated in various cancers were identified, shedding light on the potential role of the T. annulata exported protein family NIDP in host cell transformation and cancer-related pathways. IMPORTANCETurboID proximity labelling was used to unveil the secreted proteins of Theileria annulata, an apicomplexan parasite responsible for a fatal, proliferative disorder in cattle, representing a significant socio-economic burden particularly in north Africa, central Asia, and India. Our investigation has provided important insights into the unique host-parasite interaction, revealing effector proteins characterized by high intrinsically disordered protein (IDP) structures. Remarkably, these proteins are conspicuously absent in non-transforming Theileria species, strongly suggesting their central role in the transformative processes within host cells. In addition, our study identified a novel tandem arrayed protein family, with Nuclear Intrinsically Disordered Protein (NIDP) 2 emerging as a central player interacting with established tumor genes. Significantly, this work represents the first unbiased screening for exported effector proteins in Theileria and contributes essential insights into the molecular intricacies behind the malignant transformation of immune cells.

microbiology↗

bioRxiv2022

Rotavirus spike protein VP4 mediates viroplasm assembly by association to actin filaments

The formation of viroplasms is a well-conserved step in the rotavirus (RV) life cycle. In these structures, both virus genome replication and progeny assembly take place. A stabilized microtubule cytoskeleton and lipid droplets are required for the viroplasm formation, which involves several virus proteins. The viral spike protein VP4 has not previously been shown to have a direct role in viroplasm formation. However, it is involved with virus-cell attachment, endocytic internalization, and virion morphogenesis. Moreover, VP4 interacts with actin cytoskeleton components, mainly in processes involving virus entrance and egress, and thereby may have an indirect role in viroplasm formation. In this study, we used reverse genetics to construct a recombinant RV, rRV/VP4-BAP, which contains a biotin acceptor peptide (BAP) in the K145-G150 loop of the VP4 lectin domain, permitting live monitoring. The recombinant virus was replication competent but showed a reduced fitness. We demonstrate that rRV/VP4-BAP infection, as opposed to rRV/wt infection, did not lead to a reorganized actin cytoskeleton as viroplasms formed were insensitive to drugs that depolymerize actin and inhibit myosin. Moreover, wt VP4, but not VP4-BAP, appeared to associate with actin filaments. Similarly, VP4 in co-expression with NSP5 and NSP2 induced a significant increase in the number of viroplasm-like structures. Interestingly, a small peptide mimicking loop K145-G150 rescued the phenotype of rRV/VP4-BAP by increasing its ability to form viroplasms and hence, improve virus progeny formation. Collectively, these results provide a direct link between VP4 and the actin cytoskeleton to catalyze viroplasm assembly. IMPORTANCEThe spike protein VP4 participates in diverse steps of the rotavirus (RV) life cycle, including virus-cell attachment, internalization, modulation of endocytosis, virion morphogenesis, and virus egress. Using reverse genetics, we constructed for the first time a recombinant RV, rRV/VP4-BAP, harboring a heterologous peptide in the lectin domain (loop K145-G150) of VP4. The rRV/VP4-BAP was replication-competent but with reduced fitness due to a defect in the ability to reorganize the actin cytoskeleton, which affected the efficiency of viroplasm assembly. This defect was rescued by adding a permeable small-peptide mimicking the wild-type VP4 loop K145-G150. In addition to revealing a new role of VP4, our findings suggest that rRV harboring an engineered VP4 could be used as a new dual vaccination platform providing immunity against RV and additional heterologous antigens.

microbiology↗

bioRxiv2021

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

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.

microbiology↗