Biology subjects

Eberle, R. J.

Publications and source records attributed to Eberle, R. J..

8 recordsLinked to original sources

bioRxiv2026

Structural Mapping of the EIN2-EIN3 Interaction Core and Its Integration with ENAP1 in Ethylene Signaling

Ethylene regulates diverse developmental processes, yet the molecular function of its central regulator, ETHYLENE INSENSITIVE 2 (EIN2), has remained unclear. Although EIN2 nuclear import is mediated by the Importin-/{beta} pathway, the molecular events initiated by EIN2 after nuclear entry were unknown. Here we show that EIN2 directly engages the transcription factor EIN3, establishing a mechanistic link between EIN2 nuclear accumulation and transcriptional activity. Microscale thermophoresis, yeast two-hybrid analysis and in planta FLIM-FRET consistently support this interaction. Domain mapping identifies EIN3 residues 86-173 as the core EIN2-binding region, and structural modeling refines the interface to a conserved segment within residues 86-120 that contacts a conserved region near the N-terminus of the EIN2-CEND fragment. In planta, EIN2 residues 1042-1214 are sufficient for EIN3 binding, revealing multiple interaction-competent surfaces with distinct affinities. The chromatin-associated protein ENAP1 also binds EIN2 and competes with EIN3, indicating a dynamic, concentration-dependent regulatory mechanism rather than a stable ternary complex. These findings define the molecular basis of the EIN2-EIN3 interaction and provide a mechanistic framework for EIN2-dependent transcriptional control in ethylene signaling.

plant biology↗

bioRxiv2025

Inhibition of Chikungunya virus nsP2 protease in vitro by pantinin-1 isolated from scorpion venom

Climate change has enhanced the spread of arboviruses such as Chikungunya virus (CHIKV). CHIKV is a re-emerging virus from the family Togaviridae that has spread globally, causing numerous outbreaks. The lack of antiviral therapy against CHIKV makes it a significant threat to public health. Cleavage of the viral polyprotein depends on the catalytic activity of nsP2, which is essential for viral replication. Due to this critical role, the nsP2 protease is a promising target for antiviral drug development. Animal venom-derived peptides have shown great potential against a variety of diseases, including infections, cancer, and neurodegenerative disorders. In this study, we evaluated the inhibitory effects and properties of pantinin-1, a peptide derived from the scorpion Pandinus imperator with broad antimicrobial activity, against CHIKV nsP2 protease. Pantinin-1 effectively inhibited CHIKV nsP2 protease, with a half-maximal inhibitory concentration (IC50) of 6.4 {+/-} 2.04 {micro}M and complete inhibition at 175 {micro}M. Further analysis revealed that pantinin-1 acts as a competitive inhibitor with low micromolar affinity and showed no toxicity up to 20 {micro}M in cell culture. Lastly, using molecular docking with subsequent molecular dynamics, the protein-peptide interaction was analyzed, and the key residues involved in the interaction with the protease were predicted. These findings highlight the potential inhibitory effect of pantinin-1 as a lead candidate targeting nsP2 protease.

biochemistry↗

bioRxiv2025

Single-Stranded nucleic acid binding enhances the in vitro catalytic activity of Chikungunya virus nsP2 protease

Chikungunya virus (CHIKV) is an emerging arbovirus whose replication relies on the multifunctional nonstructural protein 2 (nsP2), particularly its viral protease (nsP2pro), which is essential for polyprotein processing. In this study, we investigated how interactions with nucleic acids influence nsP2pro activity. Using high-throughput sequencing-fluorescent ligand interaction profiling, we identified specific single-stranded DNA aptamers that enhanced nsP2pro activity. Additionally, both random single-stranded DNA and single-stranded RNA were found to stimulate protease activity, whereas double-stranded DNA showed no such effect. Circular dichroism spectroscopy and secondary structure predictions confirmed that the identified aptamers adopt stable folded conformations. Similarly, structured RNA sequences were also capable of promoting protease activity. The observed stimulatory effect depended on the nucleic acid strand type, length, and buffer conditions, suggesting the involvement of electrostatic interactions. Molecular docking analyses further let us assume that these nucleic acids interact specifically with the nsP2pro methyltransferase domain. Our findings provide novel insights into the regulation of nsP2pro, enhancing our understanding of CHIKV replication mechanisms, and may guide future antiviral development strategies.

biochemistry↗

bioRxiv2023

Tau protein aggregation associated with SARS-CoV-2 main protease

The primary function of virus proteases is the proteolytic processing of the viral polyprotein. These enzymes can also cleave host cell proteins, which is important for viral pathogenicity, modulation of cellular processes, viral replication, the defeat of antiviral responses and modulation of the immune response. It is known that COVID-19 can influence multiple tissues or organs and that infection can damage the functionality of the brain in multiple ways. After COVID-19 infections, amyloid-{beta}, neurogranin, tau and phosphorylated tau were detected extracellularly, implicating possible neurodegenerative processes. The present study describes the possible induction of protein aggregation by the SARS-CoV-2 3CL protease (3CLpro) possibly relevant in neuropathology, such as aggregation of tau, alpha-synuclein and TPD-43. Further investigations demonstrated that tau was proteolytically cleaved by the viral protease 3CL and, consequently, generated aggregates. However, more evidence is needed to confirm that COVID-19 is able to trigger neurodegenerative diseases.

biochemistry↗

bioRxiv2022

The secreted metabolome of HeLa cells under effect of Crotamine, a cell-penetrating peptide from a rattlesnake using NMR-based metabolomics analyses

Sequestering and reprogramming of cellular metabolism represents one of the principal hallmarks several cells. Antimicrobial peptides have been shown to exhibit selective anticancer activities. In this study, the secreted metabolome of HeLa cells under action of the antimicrobial peptide Crotamine was evaluated. Although, Crotamine has been shown to be selective for highly proliferating cells and is able to extend the in vivo lifespan. The present study using a cell line of cervical cancer, HeLa cells provide insights into how Crotamine acts in cell metabolism. NMR spectroscopy was used to identify and quantify relative metabolite levels, which are associated with Crotamine uptake. Statistical analysis reveals that Crotamine dramatically affects metabolites related to glycolysis, metabolism and biosynthesis of amino acids and pyruvate metabolism. The developed machine learning model is found to be robust by ROC curve analysis, suggesting that the metabolic state of HeLa cells treated with Crotamine is different from the control samples. To account for metabolite levels, it is suggested that Crotamine would have to act on glycolysis, which, in turn, affects several other metabolic pathways, such as, glutathione metabolism, TCA cycle and pyruvate metabolism. The observed metabolic changes shed light into the mode of Crotamine function.

cell biology↗

bioRxiv2021

Design of D-amino acids SARS-CoV-2 Main protease inhibitors using the cationic peptide from rattlesnake venom as a scaffold

The C30 Endopeptidase (3C-like protease; 3CLpro) is essential for the life cycle of SARS-CoV-2 (severe acute respiratory syndrome-coronavirus-2) since it plays a pivotal role in viral replication and transcription and is hence a promising drug target. Molecules isolated from animals, insects, plants or microorganisms can serve as a scaffold for the design of novel biopharmaceutical products. Crotamine, a small cationic peptide from the venom of the rattlesnake Crotalus durissus terrificus has been the focus of many studies since it exhibits activities such as analgesic, in vitro antibacterial and hemolytic activities. The crotamine derivative L-peptides (L-CDP) that inhibit the 3CL protease in the low {micro}M range were examined since they are susceptible to proteolytic degradation; we explored the utility of their D-enantiomers form. Comparative uptake inhibition analysis showed D-CDP as a promising prototype for a D-peptide-based drug. We also found that the D-peptides can impair SARS-CoV-2 replication in vivo, probably targeting the viral protease 3CLpro.

biochemistry↗

bioRxiv2020

In silico investigation of Aedes aegypti male-determining factor (NIX): RNA recognition motif-3, structural model and selective nucleic acid binding mode.

Mosquito borne viruses and their corresponding human infections have a fast growing impact on worldwide public health systems; in particular, Aedes aegypti and Aedes albopictus are transmitting these viruses. Only female mosquitoes bite and spread diseases. Male development in A. aegypti is initiated by male determining factors. These factors are potential candidates for the implementation of vector control strategies. Where at an early stage in gender development female mosquitoes are converted into harmless males. Among these factors, a novel gene, NIX, has been identified that shares moderate identity with transformer-2, one of the key sex-determination genes in Drosophila melanogaster. Hall et al. 2015 described two RNA recognition motifs (RRMs) in the NIX sequence, but a UniProt database search showed that A. aegypti NIX contains three RNA RRM. A homology model of NIX_RRM-3 was generated to investigate the interaction with RNA using molecular dynamics simulations. The sequence AGACGU was the most interesting result. During the binding process A1, G2 and G5 adopt an unusual syn conformation. The results let assume that the C-terminus of NIX_RRM-3 is involved in the recognition process of the target RNA motif (e.g. AG) and controls the interaction between target RNA and A. aegypti NIX.

bioinformatics↗

bioRxiv2020

The repurposed drugs suramin and quinacrine inhibit cooperatively in vitro SARS-CoV-2 3CLpro

Since the first report of a new pneumonia disease in December 2019 (Wuhan, China) up to now WHO reported more than 50 million confirmed cases and more than one million losses, globally. The causative agent of COVID-19 (SARS-CoV-2) has spread worldwide resulting in a pandemic of unprecedented magnitude. To date, no clinically safe drug or vaccine is available and the development of molecules to combat SARS-CoV-2 infections is imminent. A well-known strategy to identify molecules with inhibitory potential against SARS-CoV-2 proteins is the repurposing of clinically developed drugs, e.g., anti-parasitic drugs. The results described in this study demonstrate the inhibitory potential of quinacrine and suramin against SARS-CoV-2 main protease (3CLpro). Quinacrine and suramin molecules present a competitive and non-competitive mode of inhibition, respectively, with IC50 and KD values in low M range. Using docking and molecular dynamics simulations we identified a possible binding mode and the amino acids involved in these interactions. Our results suggested that suramin in combination with quinacrine showed promising synergistic efficacy to inhibit SARS-CoV-2 3CLpro. The identification of effective, synergistic drug combinations could lead to the design of better treatments for the COVID-19 disease. Drug repositioning offers hope to the SARS-CoV-2 control.

biochemistry↗