Biology subjects

Hernandez, G. G.

Publications and source records attributed to Hernandez, G. G..

3 recordsLinked to original sources

bioRxiv2025

Crown protein is dispensable for OmRV entry but required for efficient transmission

Non-enveloped icosahedral dsRNA viruses, such as taxons of the Totiviridae family, have evolved surface features that enable infection of multicellular hosts through receptor binding and membrane penetration via the canonical endosomal pathway. Unlike Totiviruses that infect unicellular hosts, toti-like viruses, including artiviruses, infect invertebrate multicellular hosts and possess an additional surface crown protein (CrP) on their conserved T=1 icosahedral capsid. The mosquito-specific artivirus Omono River virus (OmRV) also expresses this CrP, which has been suggested to facilitate viral infection and propagation, although it may not be essential. To clarify its role in viral infection, we generated a CrP deletion mutant of OmRV to directly assess its functional significance. The absence of CrP does not affect infectivity in mosquito cells or alter the capsid structure. However, CPE and viral propagation are still affected. These findings indicate that CrP is dispensable for OmRV infection but may play a crucial role in later stages of cell-to-cell transmission, providing important insight into its previously unclear function in the viral life cycle.

microbiology↗

bioRxiv2025

Heat tolerance of tropical herbaceous plants increases with elevation

Background and AimsTropical plants are assumed to be especially vulnerable to global warming because their physiologies are adapted to relatively constant temperatures throughout the year. Furthermore, it has been found that woody plants in colder high elevation environments are less tolerant to high temperatures than plants in the warmer lowlands. Here, we examined heat tolerance in a group of herbaceous plants with a wide elevational distribution in the tropics. MethodsThis study focused on 61 species from the order Zingiberales (ginger and banana-like plants) distributed from the lowlands (50 m asl) to lower montane forests (2000 m asl) along the Barva elevational gradient in Costa Rica. This study addressed the following questions: a) Does heat tolerance of Zingiberales species differ along the elevational gradient? b) Does heat tolerance vary along the elevational gradient within families of Zingiberales? c) Does heat tolerance vary along the elevational gradient within species for those with broad elevational distributions? To test if the temperature that causes damage to the function of photosystem II (PSII) in Zingiberales is associated with the temperatures prevalent at their elevation, we estimated heat tolerance (T50) of PSII using chlorophyll fluorescence techniques. Key ResultsIn contrast to the results found in tropical trees, our results showed that T50 is higher at higher elevations than in the lowlands for herbaceous plants species. This trend was observed across plant communities and families, and within most species with wide distributions along the elevational gradient. ConclusionsOur study suggests that herbs differ from trees in their elevational patterns in heat tolerance. We hypothesize that maximum and minimum leaf temperatures, and UV radiation may play a role in the observed pattern.

ecology↗

bioRxiv2024

Dynamic ensembles of SARS-CoV-2 N-protein reveal head-to-head coiled-coil-driven oligomerization and phase separation

The SARS-CoV-2 nucleocapsid (N) protein is essential for the viral lifecycle, facilitating RNA packaging, replication, and host-cell interactions. Its ability to self-assemble and undergo liquid-liquid phase separation (LLPS) is critical for these functions but remains poorly understood. Using an integrated approach combining small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR) spectroscopy, computational modeling, and biophysical assays, we uncover key mechanisms underpinning N-proteins dynamic self-assembly. We show that the N-proteins interdomain linker (IDL) contains a conserved coiled-coil (CC) motif that drives transient interactions between protein subunits, enabling the formation of progressively larger complexes at higher concentrations. SAXS analysis and ensemble modeling reveal that the IDL exists in a concentration-dependent equilibrium between monomeric, dimeric, and trimeric states. The CC motif facilitates parallel, head-to-head oligomerization of N-protein dimers, transitioning between compact (closed) and extended (open) configurations depending on the interaction network within the IDL. This linker-driven assembly modulates LLPS, impacting the size, stability, and dynamics of biomolecular condensates. Here, we present the most comprehensive conformational landscape analysis of the N-protein to date, providing a detailed model of its self-assembly and LLPS. Our findings highlight how the structural plasticity of the IDL and CC-mediated interactions are pivotal to its roles in the SARS-CoV-2 lifecycle.

biophysics↗