Journal of Molecular Graphics and Modelling

Chlamydia trachomatis is an obligate intracellular Gram-negative pathogen responsible for sexually transmitted infections and trachoma in humans. Although antibiotics are generally effective against acute infections, persistent chlamydial forms often exhibit reduced susceptibility during chronic infection. Chlamydia relies on its type III secretion system (T3SS) to inject effector proteins into host cells, making T3SS proteins attractive targets for antivirulence therapeutics. In this study, we employed an integrated computational pipeline to model and assemble the C. trachomatis T3SS constituent proteins. Template-based modeling using crystallographic structures of homologs from other Gram-negative bacteria revealed a highly conserved structural architecture despite low sequence identity (18-46%). Stereochemical validation confirmed high model quality, with most T3SS proteins exhibiting favorable protein-protein interactions (PPIs). Since the activity of the T3SS complex relies on extensive PPIs, we targeted these PPIs as a promising approach to attenuate bacterial virulence. CdsN, which functions as an ATPase of the T3SS, is a hexamer of which we targeted the dimerization interface. Structure-based virtual screening of compounds from the e-Drug3D and IMPPAT libraries against predicted hotspot residues and the identified druggable pocket at the CdsN dimeric interface, followed by ADMET screening, yielded three promising candidates: M Roflumilast (Drug ID: 1537), Elacestrant (Drug ID: 2081), and Tecovirimat (Drug ID: 1889). All three ligands formed thermodynamically stable complexes with the CdsN dimer, with Elacestrant demonstrating the most favourable binding free energy. This was also confirmed by 100 ns molecular dynamics simulation. This study provides new insights into the molecular architecture of C. trachomatis T3SS and identifies M Roflumilast, Elacestrant, and Tecovirimat as potential drug candidates against chlamydial infection. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/723290v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@1821599org.highwire.dtl.DTLVardef@1581baaorg.highwire.dtl.DTLVardef@1805e98org.highwire.dtl.DTLVardef@c25e56_HPS_FORMAT_FIGEXP M_FIG C_FIG

Cholera, caused by Vibrio cholerae, continues to pose a serious global public health challenge, with its impact worsened by rising antibiotic resistance associated with bacterial biofilm formation. This study reveals the role of the hypothetical protein (HP) TYC33605.1 in cyclic-di-GMP (c-di-GMP)-mediated biofilm regulation and identifies natural inhibitors that disrupt this mechanism. Functional annotation revealed TYC33605.1 as a membrane-associated diguanylate cyclase (DGC) with GGDEF and sensory domains, critical for c-di-GMP synthesis and biofilm persistence. Homology modelling and molecular dynamics (MD) simulations validated its stable 3D structure (C-score: -1.22, Ramachandran favoured regions: 91.1%) and dynamic behaviour (average RMSD: 8.55 [A]). Virtual molecular docking screening of 1,092 natural compounds identified Luteolin (CID 5280445) and Sativanone (CID 13886678) as top candidates, exhibiting strong binding affinities (-9.1 and -9.0 kcal/mol, respectively) and forming hydrogen bonds, {pi}-cation, and hydrophobic interactions with key residues (Glu293, Arg364, Ala176). MD simulations (100 ns) confirmed complex stability, with Luteolin and Sativanone showing lower RMSD fluctuations (7.78 [A] and 8.13 [A]) compared to the control and apoprotein. The ADME/Tox profiles highlighted favourable pharmacodynamics (PD), pharmacokinetics (PK), high gastrointestinal absorption, no hepatotoxicity, and drug-likeness (Lipinski compliance). Principal component, probability density function, and binding free energy analyses underscore ligand-induced conformational stability. This study proposes the molecular characterisation of the HP and the bioactive compounds Luteolin and Sativanone as promising inhibitors targeting TYC33605.1, offering a novel strategy to combat biofilm-mediated antibiotic resistance and a framework for analogous antimicrobial discovery in Vibrio cholerae.

Pseudomonas aeruginosa, a Gram-negative opportunistic pathogen is well known for life-threatening acute infections among the human population. The bacterium can withstand most antibiotics by using their high levels of inherent and acquired resistance mechanisms such as Biofilm-EPS, Persistence, and Quorum sensing (QS). Owing to the importance of adaptive antibiotic multi-drug resistance of P. aeruginosa, the current investigation is aimed to explore the phytochemicals derived from mangrove plants as potential agents to control biofilm and drug resistance mechanisms through a multi-mechanistic computational approach. For identifying potential compounds and target, In-silico drug repurposing technique is implemented by docking/virtual screening of 49 phytochemical compounds against 18 proteins involved in the Persister Cell formation, QS, and EPS synthesis in P. aeruginosa which resulted the proteins RelA and SpoT (persistence), PqsA, and PqSR (QS), and PelA and PelB (EPS synthesis) and compounds Taraxerone and Taraxerol to be potential. The results of docking were well corroborated with MD simulations. These targets and compounds explored through in-silico approach, are found to target potential antimicrobial pathways involving EPS synthesis, persistence genes, and QS, aiming to enhance antibiotic efficacy. Further, this study could be reference for in-vivo and in-vitro investigations to evaluate the further effectiveness of the compounds and potentiality of the proteins for MDR therapeutics of P. aeruginosa.

Cryptosporidium parvum is a protozoan parasite responsible for cryptosporidiosis, significantly threatening immunocompromised individuals, particularly HIV/AIDS patients, by causing severe diarrhea and potential mortality. Current treatments are largely ineffective, prompting investigations into new therapeutic options. This study evaluated two antiparasitic drugs: Mebendazole, used for helminth infections, and Artemisinin, used for malaria. The SKSR gene family encodes virulence factors in C. parvum, and Calcium-dependent protein kinase1 (CpCDPK1) regulates the life cycle of C. parvum; targeting these proteins may reduce growth and infection in hosts. In the current study, molecular docking was conducted taking Mebendazole and Artemisinin drugs as ligands, SKSR gene family and CpCDPK1 proteins as drug targets. Results with SKSR showed binding energy of -4.9 kcal/mol, -6.72 kcal/mol for Mebendazole and Artemisinin, respectively. Whereas, with CpCDPK1, the binding energies were -6.44 kcal/mol, -9.18 kcal/mol for Mebendazole and Artemisinin, respectively. Docking of Nitazoxanide (an in-use drug for C. parvum) with SKSR and CpCDPK1 revealed binding energies -4.2 kcal/mol, -4.81 kcal/mol, respectively. The stability of the proteins (targets) upon binding to the ligands was assessed by performing all-atom MD simulations for 100ns using the GROMACS package. No major variations were observed upon binding of Artemisinin and Mebendazole to SKSR and CpCDPK1. The findings of MD simulations imply that both proteins maintain their stability upon binding of Artemisinin and Mebendazole. Molecular Docking and MD simulation studies suggest that Artemisinin and Mebendazole are potential candidates for repurposing in the treatment of C. parvum infections, with recommendations for in vitro studies to validate these findings.

Human African trypanosomiasis, caused by a protozoan parasite Trypanosoma brucei, is a neglected tropical disease for which well-tolerated, conveniently administered, and highly efficacious medicines are still missing. Previously, T. brucei Phosphofructokinase was targeted by small-molecule inhibitor development efforts. This approach has shown promise both in vitro and in vivo. In this study, we have used these wet-lab results, evaluated the compounds already characterised by Molecular Dynamics simulations, found relationships between in silico and wet-lab data and used these observations to evaluate compounds that we selected through several different approaches of virtual screens. We observed that inhibitor-ATP interactions are highly predictive of the inhibitory activity. Several compounds selected through virtual screens have outperformed previously characterised compounds.

Acinetobacter baumannii is a leading multidrug-resistant critical priority pathogen in healthcare settings, where biofilm formation confers survival and antibiotic tolerance. Targeting virulence associated proteins offers an alternative to conventional bactericidal strategies. Here, the inner membrane anchored lipoprotein NLPA, implicated in biofilm associated adaptation, was studied as a putative anti-virulence target using an integrated in silico pipeline and complementing the computational findings. The Alpha fold-derived structure of NLPA served as the basis for virtual screening of approximately 1.6 million compounds, with subsequent prioritization guided by MM/GBSA calculated binding free energies to highlight the top promising candidates. Molecular dynamics simulations demonstrated stable NLPA ligand complexes, as indicated by equilibrated RMSD, low residue fluctuations in the binding region, and persistent interaction networks over time. Pharmacokinetic evaluation indicated that the compounds satisfied Lipinskis Rule of Five and had overall acceptable ADMET characteristics. Two compounds, NLPA-6 and NLPA-3, showed the most favourable predicted binding free energies, suggesting strong and stable interactions within the NLPA binding site. NLPA-3 was evaluated in vitro against A. baumannii to validate the computational outcomes. The compound displayed moderate antibacterial activity with a MIC of 125 g/mL and demonstrated 55.75% inhibition of biofilm formation at 4x MIC. In addition, in macrophage infection studies, NLPA-3 decreased intracellular bacterial survival to 19.25% at 50 g/mL, suggesting that it may disrupt virulence pathways linked to persistence. In whole, these findings identify promising NLPA targeting compounds and support the feasibility of NLPA as an anti-virulence target.

Migraine headaches affect over one billion people internationally and can be defined as episodes of acute severe pain wrapping around the head and are normally accompanied by nausea, blurry vision, and sensitivity to light and sound. While triggers that cause migraines may vary among patients, evidence shows they are involved with the trigeminovascular system (a network of blood vessels in the brain in conjunction with the trigeminal nerve). Activation of the trigeminal neurons triggers the release of vasoactive neuropeptides, such as calcitonin gene-related peptide (CGRP), leading to neurogenic inflammation and vasodilation of cranial blood vessels. The development of 5-HT1B serotonin agonist drugs, commonly known as triptans, have been an effective measure of migraine relief. The drugs created in this research were found to have improved docking scores within the 5-HT1B binding site compared to that of naratriptan. The two drugs proposed in this paper would need to undergo further investigation to determine the feasibility of laboratory synthesis and clinical trials.

The protozoan parasite Trypanosoma brucei is implicated in deadly African sleeping sickness. Experimental studies show that T. brucei codes for three aquaporin homologs (TbAQP1 to TbAQP3). TbAQP2 has been established as the high affinity drug transporter of drugs pentamidine and melarsoprol. Mutation in TbAQP2 or its loss result in pentamidine-melarsoprol cross-resistance. TbAQP2 is also shown to transport water, glycerol and other solutes to respond to osmoregulation in the infected hosts or glycerol metabolism. Experimentally determined structures of TbAQP2 shows that it adopts the same aquaporin-like hourglass helical fold. However, the so called aromatic/arginine selectivity filter (Ar/R SF) in TbAQP2 has neither arginine nor aromatic residue and all four residues are hydrophobic. Mutation and functional studies have demonstrated the role of Ar/R SF residues in the transport and selectivity of solutes in aquaporin homologs. The intriguing question is how the completely hydrophobic Ar/R SF region enables the transport of water and glycerol molecules. In this study, we used computational approach to elucidate the molecular mechanism of water and glycerol transport. Our equilibrium molecular dynamics simulations showed that the number of water molecules transported by TbAQP2 is almost one order of magnitude higher than that of prototype water channel AQP1. Moreover, the residence time within TbAQP2 channel is much less compared to that found in AQP1. The relatively wider constriction, interactions of water molecules with the selectivity filter residues and the contact duration, all contribute to a large number of water molecules transported through TbAQP2 channel. Our umbrella sampling studies show that when glycerol is transported through TbAQP2, it participates in interactions with channel residues that can be considered as complimentary to that observed in prototype glycerol transporter GlpF. Our studies reveal the molecular mechanism of water and glycerol transport in TbAQP2 and establish that TbAQP2 is an efficient water transporter. Statement of SignificanceTrypanosoma brucei causes African sleeping sickness and a homolog of aquaporin, TbAQP2, is involved in the transport of drugs that are used to treat this disease. Developing anti-parasitic drugs requires the knowledge of molecular mechanism of the proteins function. TbAQP2 has been shown to transport water and glycerol. Permeating solutes have to pass through a narrow constriction region formed by all hydrophobic residues. In the present study, equilibrium molecular dynamics simulations showed that TbAQP2 transports water molecules faster in large quantity in comparison with mammalian AQP1. Higher water transport is due to relatively wider constriction and minimum water interactions with selectivity filter hydrophobic residues. Permeating glycerol molecule is involved in complementary interactions with the channel residues. Our studies reveal how water and glycerol are transported through hydrophobic selectivity filter in TbAQP2.

Heat shock protein 90 (HSP90) assists protein folding and maturation of many important signaling proteins. In various diseases, HSP90 clients contribute to aberrant signaling, and HSP90 inhibition is being explored as a potential therapeutic approach. Commonly researched HSP90 inhibitors target the ATP-binding pocket, thereby disrupting the ATP-induced closure of HSP90. Drugs disrupting the HSP90 ATPase cycle by targeting the closed state of the chaperone have not been developed. Here, we present de novo design and selection of protein binders interacting exclusively with the closed state HSP90. Two such binders, H2 and H4, were identified that feature a similar fold and comparable affinities for HSP90 but display different binding kinetics. The structures of the HSP90 complexes with H2 and H4 were determined by cryo-EM single particle analysis, and they revealed high accuracy of the BindCraft predictions. H2 and H4 compete with p23 at one but not both symmetrical p23 binding sites on HSP90. H2 expressed in HEK293T cells moderately elevated expression of HSP70 and had no effect on the HSP90 level, suggesting muted heat shock response. Overall, this study demonstrates that the de novo binders represent novel and promising tools to probe the potential utility of HSP90 inhibition by targeting its closed state.

The Na+/K+-ATPase (NKA) regulates ion balance in the kidney and influences cellular processes like proliferation and apoptosis through its signal transduction. The endogenous ligand 20-Hydroxyeicosatetraenoic acid (20-HETE) contributes to inflammation and fibrosis in chronic kidney disease (CKD) and inhibits NKA activity in renal tubules. However, the molecular mechanism of this interaction remains unclear. In this study, we used in-silico approach to investigate the potential interaction between 20-HETE and NKA. Various ligands, including known NKA ligands such as cardiotonic steroids (CTS), 20-HETE, and negative controls, were docked using rigid and Induced Fit Docking to predict the affinity of the ligands toward NKA. Binding free energy calculations with the Prime Molecular mechanics with generalized Born and surface area (Prime MM/GBSA) tools were used to confirm the involvement of key amino acids in ligand-receptor interactions. The docking analyses revealed that 20-HETE exhibited a binding affinity comparable to negative control, with some differences between rigid and induced fit docking. Binding free energy data highlighted key amino acids in the 20-HETE and NKA interaction. Interaction fingerprint and mutations such as Ala330Gly and Val329Ala significantly reduced binding free energy, while Thr804Ala showed a notable decrease, underscoring the potential importance of these amino acids in ligand stabilization. These findings provide computational evidence supporting potential direct interaction between 20-HETE and NKA and identify candidate residues for future experimental validation.

Accurate calculation of energy changes upon mutation is a key requirement for the effective use of computational methods in protein design. In this study, we applied free energy perturbation (FEP) calculations to predict the effects of mutations on the binding free energy between the immunoglobulin subtype G (IgG) antibody fragment-crystallizable (Fc) region and the neonatal Fc receptor (FcRn), an interaction that is primarily responsible for antibody half-life. We assembled an extensive experimental dataset of Fc-FcRn binding affinities for wild-type (wt) and mutant complexes, including values from literature and from newly measured results. Starting from a crystal structure of the M252Y/S254T/T256E ("YTE") Fc variant bound to FcRn, we prepared all-atom models of human IgG1-subtype wt and YTE variant Fc-FcRn complexes, adding explicit hydrogens and assigning protonation states for key ionizable residues. Initial results using standard FEP protocols to compute relative binding free energies were promising but exhibited multiple outliers. By accounting for coupling effects for FEP mutations near key histidine residues, we improved the results for several outliers, suggesting such coupling as an important approach for pH-sensitive systems. Further, upon determining new crystal structures of four Fc variants at multiple pH values, we observed subtle conformational changes in unbound Fc; by accounting for these conformational changes in FEP calculations, we additionally improved agreement with experiment. The detailed structural and energetic analyses of the Fc-FcRn system we present here thus provide an accurate energy-calculation framework to enable rational in silico design of novel Fc variants. SignificanceThe ability to determine changes in binding affinity upon mutation is critical to structure-based protein design. In this study, we demonstrate a successful computational approach using free energy perturbation (FEP) calculations on the antibody Fc-FcRn complex, a medically relevant system with implications for both therapeutic and prophylactic antibody use. Our successful calculation of accurate binding energies across a wide range of cases speaks to the power of the FEP methodology in navigating the free energy landscapes of dynamic molecular complexes. Furthermore, we show that accurate Fc-FcRn affinity calculations required careful consideration of conformational flexibility between bound and unbound states, contributing to our functional understanding of a system that will be important for future rational antibody-design efforts. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/721095v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@f754d8org.highwire.dtl.DTLVardef@1e366beorg.highwire.dtl.DTLVardef@6e67caorg.highwire.dtl.DTLVardef@602a14_HPS_FORMAT_FIGEXP M_FIG C_FIG

The oncogenic progression of high-risk Human Papillomavirus (HPV) strains relies on the cooperative interaction between the E1 replicative helicase and the E2 origin-binding protein to initiate viral DNA amplification. Disrupting this protein-protein interaction represents a promising, yet clinically unrealized, therapeutic paradigm for treating established HPV infections prior to malignant transformation. This study presents a comprehensive computational pipeline for the de novo design and evaluation of peptide inhibitors targeting the HPV E1-E2 interface, specifically a conserved arginine triad on the solvent-exposed surface of the E1 helicase. AlphaProteo was used for sequence discovery, and AlphaFold 3 for complex structural prediction, generating a candidate library that was subsequently subjected to dual-scale Molecular Dynamics (MD) simulations and MM/GBSA thermodynamic validation using GROMACS. Binder 8 emerged as the lead candidate, yielding a predicted binding free energy of -59.1 {+/-} 0.7 kcal/mol -- a statistically significant improvement over the native E1-E2 baseline (Welchs t-test, p = 8.14e-19; Cohens d = 2.21). As an implicit solvent method, MM/GBSA overestimates absolute affinities; reported values reflect effective binding enthalpy and should be interpreted as relative rankings. Per-residue energy decomposition confirms binding is anchored through multi-point interactions with the arginine triad. Physicochemical profiling via CSM-Toxin and AlgPred 2.0 confirms zero predicted toxicity and non-allergenic properties for Binder 8. Sequence alignment across 183 oncogenic Alpha-papillomavirus genotypes demonstrates near-universal conservation of the targeted triad, supporting Binder 8 as a candidate scaffold for broad-spectrum antiviral development. These findings provide a computationally validated blueprint for future in vitro validation via Bio-layer interferometry.

Structure-based drug design has become increasingly important in the pharmaceutical industry for accelerating the discovery of effective drug candidates. In particular, ligand binding free energy serves as a critical metric for predicting drug efficacy during the key stages of hit discovery and lead optimization. Continuous progresses have been made in the prediction of ligand binding free energies, but direct comparisons of different methods using the same force field remain challenging due to their unique implementations into different simulation engines. In this study, we present a direct comparison of four popular methodologies (Amber-TI, GROMACS-NETI, OpenMM-FEP, and BLaDE-MSLD) for calculating relative binding free energies ({Delta}{Delta}Gbind) with the same Amber protein and ligand force fields using MolCube Alchemical Free Energy Simulator (MolCube-AFES), which provides an input generation workflow to support {Delta}{Delta}Gbind calculations of all four methods. We used 80 alchemical transformations (among the JACS benchmark set by Wang et al.) and two additional applications to compare the predicted {Delta}{Delta}Gbind from the four methods against experimental measurements. All four methods reproduced experimentally observed trends with most transformations within {+/-}2 kcal/mol from experiments and show broadly comparable accuracy with no statistically significant performance differences across the benchmark dataset. These results demonstrate that MolCube-AFES enables controlled, cross platform benchmarking and show that all four different alchemical free energy methods deliver statistically equivalent accuracy, with method selection guided by workflow requirements such as throughput, portability, and perturbation network design rather than expected differences in performances.

The MDM2-p53 protein-protein interaction is a validated oncology target, yet no food-derived linear peptide has been documented to engage the canonical three-anchor MDM2-p53 interface. We developed a multi-stage computational pipeline (PepVeg) to screen 22 plant and fungal proteomes (337,646 proteins) for MDM2-binding peptides, applying sequential in silico hydrolysis, physicochemical filtering, ESM-2 embedding-based dimensionality reduction, and pharmacophore-driven selection. Twenty-six candidates were evaluated by AlphaFold 3 (AF3) co-folding against MDM2(25-109), yielding 15 binders (iPTM >= 0.75; 58% of evaluated). A 36-peptide benchmark with 29 hard negatives confirmed AF3 discriminative power (Cohens d = 3.41; 95% CI: 1.94-4.88; Hedges g = 3.32; zero overlap). The lead candidate, SPAFESTWDILK -- a tryptic fragment of Zingiber officinale histone deacetylase (UniProt A0A8J5FLH2) -- was evaluated by eight computational assessments: AF3 Server (iPTM 0.83, SD 0.01), Protenix (iPTM 0.923), Chai-1 (iPTM 0.891), EvoEF2 (-55.57 EEU), two GROMACS simulations (no dissociation across two force fields), and two MM-PBSA calculations (-75.30 (SD 4.92) and -55.07 (SD 2.86) kcal/mol). The W8A point mutant produced an iPTM drop of 0.201, closely paralleling the p53 W23A drop of 0.193; we predict W8A substitution will abolish binding. SPAFESTWDILK ranked only #890/2,000 by ESM-2 similarity and was recovered solely through pharmacophore matching, demonstrating that no single pipeline stage alone is sufficient. To our knowledge, this is the first food-database-derived linear peptide with multi-convergent computational evidence supporting engagement of the canonical three-anchor MDM2-p53 interface. Experimental validation by SPR/ITC is warranted.

Artemisinin is an effective antimalarial drug sourced from Artemisia annua, but its low and variable yields require enhancement either semi-synthetically or in-planta to meet the global demand for treatment. Though essential enzymes have been identified in the artemisinin biosynthetic pathway, including an essential Cytochrome P450 monooxygenase (CYP71AV1), there are still many unknowns. Cytochrome P450 reductase 1 (herein, AaCPR1), has been experimentally confirmed as an electron transfer partner for CYP71AV1 in its three step oxygenation of key artemisinin precursors. However, the recent discovery of a highly related CPR, herein AaCPR2, introduces the possibility that another, potentially more catalytically favourable interaction, could exist for CYP71AV1. Therefore, enzyme kinetics and differential scanning fluorimetry (DSF) were used in the characterisation of both AaCPR1 and AaCPR2 to determine the existence and source of their catalytic differences. Tested enzyme activity under cytochrome c and NADPH concentrations revealed that AaCPR1 had lower Km and higher kcat/Km values, while AaCPR2 had higher Vmax and kcat values. This suggests that AaCPR1 is more effective at reducing cytochrome c when substrate conditions are limiting, whereas AaCPR2 is more effective than AaCPR1 at reducing cytochrome c when substrate conditions are saturating. This implies a functional partitioning of the two enzymes on the basis of substrate availability. The DSF results provided deeper insight into the different protein-ligand interactions between the two enzymes. AaCPR2 reached lower maximum melting temperatures across all tested conditions, whereas AaCPR1 had higher maximum melting temperatures. Thus, AaCPR1 exhibits higher thermal stability and has a higher temperature threshold than AaCPR2. This contributes to the notion that the AaCPRs are functionally divergent also on the basis of temperature. The cumulative differences in melting behaviour between the two enzymes led to the hypothesis that AaCPR1 and AaCPR2 exhibit different domain motions that may lead to preferential catalysis for one redox partner over another. This was further supported by the prediction of a highly variable loop region between the two enzymes at the connecting domain just after the flexible hinge. If such loops are highly mobile, as predicted, then the residue differences therein could provide a bio-structural basis for the kinetic and thermal/biophysical differences observed between AaCPR1 and AaCPR2. These data support that AaCPR1 and AaCPR2 possess fundamental biophysical differences despite their high degree of relatedness. Ultimately, these differences suggest differential metabolic functions of the two enzyme in artemisinin biosynthesis and/or other important secondary metabolic processes.

Burkholderia mallei, a facultative intracellular Gram-negative pathogen, is the causative agent of glanders that primarily affects solipeds and sporadically transmitted to humans. Current interventions mainly rely on antibiotics; however, increasing resistance and the lack of a licensed vaccine further complicate disease management. In the present study, a consensus-based computational framework was employed on the B. mallei turkey2 proteome. Total 59 proteins - including porins, TonB receptors, autotransporters, and efflux components - were identified as surface exposed outer membrane {beta}-barrel (OMBB) proteins that were used to design a multi-epitope vaccine (MEV) construct. B- and T-cell epitopes were predicted from 59 proteins, and ten epitopes each of cytotoxic T-lymphocyte (CTL), helper T-lymphocyte (HTL), and B-cell were chosen based on their antigenicity, non-allergenicity, non-toxicity, surface accessibility, and conservation across 32 B. mallei strains. The MEV was included with suitable adjuvants at the N-terminus to enhance its immunogenicity. The 780 amino acid MEV construct was predicted to be antigenic, and soluble upon overexpression with 62.69% random coils, while the rest formed -helices and {beta}-strands. The tertiary structure of the MEV was generated and subsequently validated, indicating good structural quality. Molecular docking of the MEV with toll-like receptor 4 (TLR4) demonstrated strong affinity, and molecular dynamics simulation confirmed the structural stability of the MEV-TLR4 complex. In-silico immune simulation showed the capability of MEV to induce a strong immune response. The study proposes an MEV construct by utilizing surface exposed OMBB proteins which directly interact with the host and serve as effective immunogenic targets against B. mallei infection. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/727591v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@10cd6d8org.highwire.dtl.DTLVardef@1ed3f0borg.highwire.dtl.DTLVardef@c6173forg.highwire.dtl.DTLVardef@1204f73_HPS_FORMAT_FIGEXP M_FIG C_FIG

Metastatic melanoma is an aggressive cutaneous malignancy frequently driven by the oncogenic V600E mutation within the BRAF kinase. While first-generation Type IS BRAF inhibitors, such as dabrafenib, are currently prescribed to target this specific molecular vulnerability, paradoxical MAPK pathway activation, and acquired drug resistance necessitate the continuous development of structurally optimized lead molecules. In this study, chemical intuition, bioisosteric replacement, and computational molecular docking were employed to propose two novel BRAFV600E drug candidates. The proposed therapeutics, engineered to incorporate constrained sp3-hybridized aliphatic rings and a sulfoximine bioisostere, demonstrated thermodynamically superior docking scores within the mutant catalytic cleft compared to dabrafenib. Lastly, a homology analysis determined that Mus musculus is a suitable model organism for future preclinical studies and confirmed crucial structural selectivity against microbial off-target kinases.

The identification of small molecule modulators of immune checkpoint proteins remains a significant challenge in drug discovery due to the flat, featureless nature of protein-protein interaction interfaces and the characteristically low hit rates observed in conventional high-throughput screening campaigns. Here we report OracleScreen-LILRB4, an ensemble machine learning framework trained on quantitative biophysical screening data from two structurally diverse compound libraries (19,800 compounds total) screened against the myeloid immune checkpoint leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3). By formulating binding prediction as a regression task targeting continuous {Delta}Fnorm values rather than binary hit classifications, OracleScreen-LILRB4 achieved a mean Spearman R of 0.61 and ROC-AUC of 0.86 under scaffold-aware cross-validation. Prospective virtual screening of a 45,760-member compound library and experimental validation of the top 200 predictions yielded a 28.5% hit rate, representing a 15.0-fold enrichment over baseline, with 16 compounds demonstrating nanomolar-affinity LILRB4 (ILT3) engagement. Lead compounds ORS-22 and ORS-14 restored anti-tumor immune activity across patient-derived colorectal cancer and acute myeloid leukemia co-culture systems, reversing SCG2-mediated immunosuppression and recovering cytotoxic T-cell function. These findings establish OracleScreen-LILRB4 as an effective computational framework for accelerating small molecule discovery against non-enzymatic immune checkpoint targets. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=99 SRC="FIGDIR/small/732859v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@1ef70a9org.highwire.dtl.DTLVardef@cd976dorg.highwire.dtl.DTLVardef@1907ebforg.highwire.dtl.DTLVardef@1716aec_HPS_FORMAT_FIGEXP M_FIG C_FIG

Resistance to {beta}-lactam antibiotics, including carbapenems, mediated by metallo-{beta}-lactamases (MBLs), including the New Delhi metallo-{beta}-lactamase (NDM) MBL subfamily, is increasing. No MBL inhibitors are currently approved for clinical use with most reported MBL inhibitors are metal ion chelators, acting either at the Zn(II) ion active site and/or in solution. The hexokinase inhibitor 3-bromopyruvate (3-BP) is reported to inhibit NDM-1. We found that 3-BP selectively restored the antimicrobial activity of meropenem against carbapenem resistant Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii strains, obtained from clinical and environmental isolates from Tanzania and Malawi, containing genes that encode NDM-1 or NDM-5, but not against strains containing genes encoding for serine {beta}-lactamases. Mass spectrometry studies with NDM-1 and NDM-5 support a mechanism involving covalent reaction of 3-BP with an active site cysteine residue. The results will promote work on the development of covalently reacting MBL inhibitors, a strategy that has been successful for inhibition of the nucleophilic serine {beta}-lactamases.

Epstein-Barr virus (EBV) is an oncogenic virus which is responsible for various malignant as well as non-malignant diseases and leads to about 200,000 deaths each year. Despite efforts, there are no FDA-approved drugs targeting EBV. Reactivation of EBV plays a critical role in the transition from latency to lytic cycle, leading to viral replication and disease progression, and is primarily regulated by the transactivator BZLF1. In this study, we combined computational screening with experimental validation to identify repurposing drugs that inhibit EBV reactivation and replication. FDA-approved compounds predicted using in-house AI/ML-based model (Anti-EBV) and miRNA-seq and RNA-seq analyses, were selected for further evaluation. Molecular docking against BZLF1, supported by in silico alanine scanning to identify critical DNA-binding residues, led to the selection of seven candidate drugs. Among these, an antimalarial drug, dihydroartemisinin (DHA), showed the strongest inhibitory activity in vitro, with an IC99 of 1 {micro}M and an SI Index of 113.5. DHA reduced both EBV viral copy number and the expression of early and late lytic genes. Molecular docking and simulation studies demonstrated stable binding of DHA within the BZLF1 DNA-binding pocket, inhibiting the key residues involved in BZLF1 activation and DNA binding. Analysis at the gene level confirmed its inhibitory effect on EBV replication, while expression analysis at the transcriptional and protein levels, along with immunofluorescence analysis, indicated its inhibitory effect on EBV reactivation and virion assembly. These findings suggest DHA as a promising repurposing antiviral candidate targeting EBV lytic proteins and offers an effective target-based therapeutic strategy. ImportanceThis study identifies a repurposed small-molecule inhibitor of EBV reactivation and replication. Here, we proposed target-based therapy, integrating computational and experimental approaches to target the EBV lytic transactivator BZLF1. Since early lytic EBV protein BZLF1 plays a critical role in viral reactivation and replication, inhibition of its activation and DNA-binding function represents a promising therapeutic approach to prevent EBV infection. Molecular docking and simulation studies revealed stable binding of DHA within the BZLF1 DNA-binding pocket. Furthermore, in vitro analyses demonstrated significant inhibition of viral gene copy number and reduced mRNA and protein levels of key lytic proteins. Thus, this study demonstrated DHA as a safe and effective repurposed therapeutic candidate against EBV infection.