Amino Acid Residues Research Articles

SAXS, DLS, and MD studies of the Rg/Rh ratio for swollen and collapsed dendrimers.

The radius of gyration, Rg, and the hydrodynamic radius, Rh, are the main experimental parameters that characterize the size of linear and branched macromolecules. In the case of dendrimers in solution, the ratio Rg/Rh, depending on the global conformation, varies from 1 (for a Gaussian soft sphere) to 3/5 (for a hard sphere). However, for high-generation dendrimers, this ratio may be less than the limiting value for a hard sphere. To understand the reasons of the low Rg/Rh value (<0.77), we have studied the second-generation peptide dendrimer containing pH-sensitive histidine amino acid residues (Lys-2His dendrimer) using small-angle x-ray (SAXS) and dynamic light scattering (DLS) experiments, as well as molecular dynamics simulations. The Lys-2His dendrimer takes a swollen conformation at pH = 2 and a collapsed 1 at pH = 7. Our results show that the Rg/Rh ratio for the considered dendrimer decreases from ≈3/5 at pH = 2 to 0.5 at pH = 7. We have found that the very low Rg/Rh value is due to (1) the formation of a dense impenetrable core (i.e., the transformation of the dendrimer from a Gaussian soft sphere into a sphere with a dense core) and (2) the presence of a larger number of solvent molecules in the dendrimer corona than in a typical macromolecule. In addition, in this work, we have directly confirmed in the experiments for the first time, the collapse of the Lys-2His dendrimer with increasing pH.

Design of ancestral mammalian alkaline phosphatase bearing high stability and productivity.

Sequence-based protein redesign methods, such as full consensus design (FCD) and ancestral sequence reconstruction (ASR), have the potential to construct new enzymes utilizing protein sequence data registered in a rapidly expanding sequence database. The high thermostability of these enzymes would expand their application in diagnostics and molecular biology. These enzymes have also demonstrated a high level of active expression by Escherichia coli. These characteristics make these APs attractive candidates for industrial application. In addition, different amino acid residues are primarily responsible for thermal stability and active expression, suggesting important implications for strategies for designing enzymes by FCD and ASR.

An in vivo and in silico probing of the protective potential of betaine against sodium fluoride-induced neurotoxicity.

Excessive fluoride exposure beyond the tolerable limit may adversely impacts brain functionality. Betaine (BET), a trimethyl glycine, possesses antioxidant, anti-inflammatory and anti-apoptotic functions, although the underlying mechanisms of the role of BET on fluoride-induced neurotoxicity remain unelucidated. To assess the mechanism involved in the neuro-restorative role of BET on behavioural, neurochemical, and histological changes, we employed a rat model of sodium fluoride (NaF) exposure. Animals were treated with NaF (9mg/kg) body weight (bw) only or co-treated with BET (50 and 100mg/kg bw) orally uninterrupted for 28 days. We obtained behavioural phenotypes in an open field, performed negative geotaxis, and a forelimb grip test, followed by oxido-inflammatory, apoptotic, and histological assessment. Behavioural endpoints indicated lessened locomotive and motor and heightened anxiety-like performance and upregulated oxidative, inflammatory, and apoptotic biomarkers in NaF-exposed rats. Co-treatment with BET significantly enhanced locomotive, motor, and anxiolytic performance, increased the antioxidant signalling mechanisms and demurred oxidative, inflammatory, and apoptotic biomarkers and histoarchitectural damage in the cerebrum and cerebellum cortices mediated by NaF. The in-silico analysis suggests that multiple hydrogen bonds and hydrophobic interactions of BET with critical amino acid residues, including arginine (ARG380 and ARG415) in the Keap1 Kelch domain, which may disrupt Keap1-Nrf2 complex and activate Nrf2. This may account for the observed increased in the Nrf2 levels, elevated antioxidant response and enhanced anti-inflammatory response. The BET-Keap1 complex was also observed to exhibit structural stability and conformational flexibility in solvated biomolecular systems, as indicated by the thermodynamic parameters computed from the trajectories obtained from a 100 ns full atomistic molecular dynamics simulation. Therefore, BET mediates neuroprotection against NaF-induced cerebro-cerebellar damage through rats' antioxidant, anti-inflammatory, and anti-apoptotic activity, which molecular interactions with Keap1-Nrf2 may drive.

Understanding the Carbyne Formation from C2H2 Complexes.

Nature chooses a high-valent tungsten center at the active site of the enzyme acetylene hydratase to facilitate acetylene hydration to acetaldehyde. However, the reactions of tungsten-coordinated acetylene are still not well understood, which prevents the development of sustainable bioinspired alkyne hydration catalysts. Here we report the reactivity of two bioinspired tungsten complexes with the acetylene ligand acting as a four-: [W(CO)(C2H2)(PymS)2] (1) and a two-electron donor: [WO(C2H2)(PymS)2] (3), with PMe3 as a nucleophile to simulate the enzyme's reactivity (PymS = 4-(trifluoromethyl)-6-methylpyrimidine-2-thiolate). In dichloromethane, compound 1 was found to react to the cationic carbyne [W≡CCH2PMe3(CO)(PMe3)2(PymS)]Cl (2-Cl) while 3 reacts to the vinyl compound [WO(CH═CHPMe3)(PMe3)3(PymS)]Cl (4-Cl). The formation of the latter follows the common rules applied to η2-alkyne complexes, whereas the carbyne formation was not expected due to the challenging 1,2-H shift. To understand these differences in behavior between seemingly similar acetylene complexes, stepwise addition of the nucleophile in various solvents was investigated by synthetic, spectroscopic, and computational approaches. In this manuscript, we describe that only a four-electron donor acetylene complex can react to the carbyne over the η1-vinyl intermediate and that 1,2-H shift can be assisted by an H-transfer reagent (in this case, the decoordinated PymS ligand). Furthermore, to favor the attack of PMe3 at W coordinated acetylene, the metal center needs to be electron-poor and crowded enough to prevent nucleophile coordination. Finally, the intricate role of the anionic PymS ligand in the vicinity of the first coordination sphere models the potential involvement of amino acid residues during acetylene transformations in AH.

The role of histone post-translational modifications in cancer and cancer immunity: functions, mechanisms and therapeutic implications

Histones play crucial roles in both promoting and repressing gene expression, primarily regulated through post-translational modifications (PTMs) at specific amino acid residues. Histone PTMs, including methylation, acetylation, ubiquitination, phosphorylation, lactylation, butyrylation, and propionylation, act as important epigenetic markers. These modifications influence not only chromatin compaction but also gene expression. Their importance extends to the treatment and prevention of various human diseases, particularly cancer, due to their involvement in key cellular processes. Abnormal histone modifications and the enzymes responsible for these alterations often serve as critical drivers in tumor cell proliferation, invasion, apoptosis, and stemness. This review introduces key histone PTMs and the enzymes responsible for these modifications, examining their impact on tumorigenesis and cancer progression. Furthermore, it explores therapeutic strategies targeting histone PTMs and offers recommendations for identifying new potential therapeutic targets.

Discovery of α-amylase and α-glucosidase dual inhibitors from NPASS database for management of Type 2 Diabetes Mellitus: A chemoinformatic approach.

Postprandial hyperglycemia, typical manifestation of Type 2 Diabetes Mellitus (T2DM), is associated with notable global morbidity and mortality. Preventing the advancement of this condition by delaying the rate of glucose absorption through inhibition of α-amylase and α-glucosidase enzymatic activities is of utmost importance. Finding a safe antidiabetic drug is essential since those that are currently on the market have drawbacks like unpleasant side effects. The current study utilized computer-aided drug design (CADD), as a quick and affordable method to find a substitute drug template that can be used to control postprandial hyperglycemia by modulating the activity of α-amylase and α-glucosidase enzymes. The Natural Products Activity and Species database (NPASS) (30,926 compounds) was screened in silico, with a focus on evaluating drug-likeness, toxicity profiles and ability to bind on a target protein. Two molecules NPC204580 (Chrotacumine C) and NPC137813 (1-O-(2-Methoxy-4-Acetylphenyl)-6-O-(E-Cinnamoyl)-Beta-D-Glucopyranoside) were identified as potential dual inhibitors for α-amylase and α-glucosidase with free binding energies of -14.46 kcal/mol and -12.58 kcal/mol for α-amylase, and -8.42 kcal/mol and -8.76 kcal/mol for α-glucosidase, respectively. The molecules showed ionic, H-bonding and hydrophobic interactions with critical amino acid residues of both enzymes. Moreover, 100 ns molecular dynamic simulations showed that both molecules are stable on the receptors' active sites based on root mean square deviation (RMSD), root mean square fluctuation (RMSF), and the Generalized Born surface area (GBSA) energy calculated. The two compounds are thus promising therapeutic agents for T2DM that merit further investigation due to their excellent binding energies, encouraging pharmacokinetics, toxicity profiles, and stability as demonstrated in simulated studies.

Vimentin as a universal receptor for pseudorabies virus infection in pig and human cells.

Pseudorabies virus (PRV), known to infect pigs and found in various species, including humans, shows zoonotic potential. This study identified vimentin (VIM), a highly conserved intermediate filament protein expressed in multiple mammalian species and tissues, as a universal receptor for PRV infections in human and porcine cells. The adsorption of PRV is positively correlated with the level of VIM expressed in different cells. Overexpression and knockdown of VIM significantly increase and decrease PRV adsorption in cells, respectively. Dot blot assay and VOPBA showed that purified VIM can directly bind to PRV virions efficiently in a dose-dependent manner. PRV and VIM are co-localized at the cell membrane of PRV-infected cells. Moreover, PRV mainly binds to host VIM via its conserved amino acid residues in PRV gD (W98, G162, Y164, C205) and gH (C439) and the Rod domain (residues 96-404) of VIM. In addition, regulating the expression of VIM also influences the entry, replication, and release of PRV, which has a similar result to the adsorption. These results demonstrate that VIM, as a universal receptor, can facilitate PRV infection in multiple stages in human and porcine cells, highlighting the zoonosis characteristics of PRV and the need for more attention.

Comparative study of the diversity of amino acids on human leucocyte antigen class II molecules in patients with acquired aplastic anaemia.

Human leucocyte antigen (HLA) class II molecules are critically involved in the pathology of acquired aplastic anaemia (AA) by regulating the immune response and autoreactive T cell-mediated haematopoietic cell death. In the study, amino acid residue variation and molecular structure of HLA class II have been initially investigated in 96 patients with AA. The frequencies of residues 9 and 57 in pocket 9 (P9) in DQB1, and amino acid positions 9, 11, 13, 16, 26, 38, 67 and 71 in the P4, P6 and P9 pockets in DRB1 were more prevalent among AA patients. By applying a multivariate recursive approach, the DRβ-Gln-16 (OR = 3.003, 95% CI = 1.468-6.145, pc = 0.003), DRβ-Ala-71 (OR = 1.924, 95% CI = 1.233-3.002, pc = 0.004) in P4/P7 and DQβ-Asp-57 (OR = 3.483, 95% CI = 1.079-11.242, pc = 0.037) in P9, these critical residues were significantly discovered as risk amino acid residues on the onset of AA, as well as associated with PNH-type cells and pathological somatic or cytogenetic mutations. In silico structural model analysis showed that identified DRβ-Ala-71 and DQβ-Asp-57 within the antigen-binding groove interacting with a more variable antigenic segments, may impact the repertoire of peptides presented, influence the interface HLA-antigen-T-cell receptor β (TCR β). These findings provided light on the immunogenetic pathophysiology of AA aetiology and their potential impact on upcoming immunotherapies.

Halogen-based quinazolin-4(3H)-one derivatives as MCF-7 breast cancer inhibitors: Current developments and structure-activity relationship.

Currently, cancer is a serious health challenge with predominance beyond restrictions. Breast cancer remains one of the major contributors to cancer-related morbidity and mortality in women. Chemotherapy continues to be crucial in the treatment of all variants of cancer. Several antitumor drugs are presently in different phases of clinical trials, whereas many more have been approved for clinical use. However, these drugs have the potential to cause adverse effects, and certain individuals may become resistant to them, which would eventually reduce the drug's efficacy. Therefore, it is essential to discover, develop, and improve newer anticancer drug molecules that could potentially inhibit proliferative pathways. In recent years, quinazolinone derivatives, more specifically halogen-substituted 4(3H)-quinazolinone, have drawn attention as a promising new class of chemotherapeutic agents. In addition, these molecules showed significant inhibition in micromolar ranges when tested in vitro against the MCF-7 cell line. Therefore, this study aims to emphasize the intriguing versatility of halogen atoms, providing an in-depth summary and highlighting recent developments in the anticancer properties of halogenated 4(3H)-quinazolinones. It also features a detailed discussion of the structure-activity relationship (SAR) of various functional groups and their interaction with amino acid residues utilizing molecular docking studies. The intent is to foster novel discoveries that can inspire innovative investigations in this domain. Hence, this study simplifies the drug design and development strategies by prolonging the array of pharmacologically active candidates.

Debittering and antioxidant improvement of soy protein hydrolysates using curcumin as hydrophobic core.

Protein hydrolysates possess various bioactive functions (e.g. antioxidant), but their bitter taste is unacceptable to most consumers. In the present study, a novel approach for debittering was introduced, which involved the utilization of a hydrophobic compound, curcumin (Cur). Soy protein hydrolysates (SPH), prepared through alcalase hydrolysis, served as the research model for this investigation. It was found that bitter intensity of SPH was dominated by the hydrophobic amino acid residues, and the addition of Cur could remarkably reduce bitterness. The debittering mechanism is attributed to the direct binding of Cur to the exposed hydrophobic amino acid residues of SPH via hydrophobic interaction, thereby shielding the hydrophobic bitter groups and hindering their interaction with the bitter taste receptors. Moreover, this debittering strategy leads to the generation of stable nanoparticles with a Cur-core/SPH-shell architecture, which can significantly improve the antioxidant capacity of SPH compared to those using biomacromolecules for encapsulation. Using curcumin as a hydrophobic core is a facile and feasible strategy with bifunction of debittering as well as improving bioactive effect of SPH, which may extend its application in foods. © 2024 Society of Chemical Industry.

Cryo-EM of human rhinovirus reveals capsid-RNA duplex interactions that provide insights into virus assembly and genome uncoating.

The cryo-EM structure of the human rhinovirus B14 determined in this study reveals 13-bp RNA duplexes symmetrically bound to regions around each of the 30 two-fold axes in the icosahedral viral capsid. The RNA duplexes (~12% of the ssRNA genome) define a quasi-dodecahedral cage that line a substantial part of the capsid interior surface. The RNA duplexes establish a complex network of non-covalent interactions with pockets in the capsid inner wall, including coulombic interactions with a cluster of basic amino acid residues that surround each RNA duplex. A direct comparison was made between the cryo-EM structure of RNA-filled virions and that of RNA-free (empty) capsids that resulted from genome release from a small fraction of viruses. The comparison reveals that some specific residues involved in capsid-duplex RNA interactions in the virion undergo remarkable conformational rearrangements upon RNA release from the capsid. RNA release is also associated with the asynchronous opening of channels at the 30 two-fold axes. The results provide further insights into the molecular mechanisms leading to assembly of rhinovirus particles and their genome uncoating during infection. They may also contribute to development of novel antiviral strategies aimed at interfering with viral capsid-genome interactions during the infectious cycle.

Biotransformation of Tetrabromobisphenol A and Its Analogs by Selected Gut Bacteria Strains: Implications for Human Health.

Knowledge of the biotransformation of tetrabromobisphenol A (TBBPA) and its related contaminants by human gut microbiota (GM) remains unexplored. Here, TBBPA and its four analogs were incubated with mixed GM strains, and nine rhamnosylated or debrominated transformation products (TPs) were discovered. Remarkably, rhamnosylation was identified as a common and unique microbial transformation pathway for these contaminants, and six of the seven rhamnosylated TPs were reported for the first time. Additionally, a kinetic transformation study also showed a rapid and strong bioaccumulation of TBBPA and TPs by Clostridium manihotivorum. Genomic analysis and phylogenetic studies identified C1.1_02053 as the gene encoding the C. manihotivorum working rhamnosyltransferase (CmRT), showing elevated gene expression with higher TBBPA exposure. Molecular docking identified five critical amino acid residues in CmRT that catalyze TBBPA rhamnosylation, and molecular dynamics simulations further confirmed the stability of the CmRT-TBBPA complex. Dynamic metabolomics analysis showed microbial growth-dependent disturbing effects in C. manihotivorum upon TBBPA exposure, and key metabolic pathways related to rhamnosyltransferase showed changes closely related to the transformation process. These findings provide insights into the unique transformation of environmental contaminants by the GM and highlight the disturbing effects of exogenous chemicals on the GM, as well as the potential impacts on overall human health.

Ultradeep O-GlcNAc proteomics reveals widespread O-GlcNAcylation on tyrosine residues of proteins

As a unique type of glycosylation, O-linked β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) on Ser/Thr residues of proteins was discovered 40 y ago. O-GlcNAcylation is catalyzed by two enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which add and remove O-GlcNAc, respectively. O-GlcNAcylation is an essential glycosylation that regulates the functions of many proteins in virtually all cellular processes. However, deep and site-specific characterization of O-GlcNAcylated proteins remains a challenge. We developed an ultradeep O-GlcNAc proteomics workflow by integrating digestion with multiple proteases, two mass spectrometric approaches (i.e., electron-transfer/higher-energy collision dissociation [EThcD] and HCD product-dependent electron-transfer/higher-energy collision dissociation [HCD-pd-EThcD]), and two data analysis tools (i.e., MaxQuant and Proteome Discoverer). The performance of this strategy was benchmarked by the analysis of whole lysates from PANC-1 (a pancreatic cancer cell line). In total, 2,831 O-GlcNAc sites were unambiguously identified, representing the largest O-GlcNAc dataset of an individual study reported so far. Unexpectedly, in addition to confirming known sites and identifying many other sites of Ser/Thr modification, O-GlcNAcylation was found on 121 tyrosine (Tyr) residues of 93 proteins. In vitro enzymatic assays showed that OGT catalyzes the transfer of O-GlcNAc onto Tyr residues of peptides and OGA catalyzes its removal. Taken together, our work reveals widespread O-GlcNAcylation on Tyr residues of proteins and that Tyr O-GlcNAcylation is mediated by OGT and OGA. As another form of glycosylation, Tyr O-GlcNAcylation is likely to have important regulatory roles.

Machine learning-based prediction of bioactivity in HIV-1 protease: insights from electron density analysis.

Aim: To develop a model for predicting the biological activity of compounds targeting the HIV-1 protease and to establish factors influencing enzyme inhibition.Materials & methods: Machine learning models were built based on a combination of Richard Bader's theory of Atoms in Molecules and topological analysis of electron density using experimental x-ray 'protein-ligand' complexes and inhibition constants data.Results & conclusion: Among all the models tested, logistic regression achieved the highest accuracy of 0.76 on the test set. The model's ability to differentiate between less active and highly active classes was relatively good, as indicated by an AUC-ROC score of 0.77. The analysis identified several critical factors affecting the biological activity of HIV-1 protease inhibitors, including the electron density contribution of hydrogen atoms, bond-critical points and particular amino acid residues. These findings provide new insights into how these molecular factors influence HIV-1 protease inhibition, emphasizing the importance of hydrogen bonding, glycine's flexibility and hydrophobic interactions in ligand binding.

Antisera-Neutralizing Capacity of a Highly Evolved Type 2 Vaccine-Derived Poliovirus from an Immunodeficient Patient

Background: The serotype 2 oral poliovirus vaccine (OPV2) can revert to regain wild-type neurovirulence and spread, causing the emergence of vaccine-derived poliovirus (VDPV2) and immunodeficiency-related vaccine-derived polioviruses (iVDPVs). In the United States, testing carried out by the CDC of type II iVDPV (iVDPV2) with human immune serum from the vaccine has shown that the presence of the virus poses a threat to eradication efforts. Methods: We analyzed the major neutralization sites of VP1, VP2, and VP3 of the iVDPV using bioinformatics techniques and homology modeling (SWISS-MODEL). The three amino acid residues 679, 680, and 141 of the P1 region changed, which had an impact on the spatial conformation of the viral-neutralizing site. We tested polio-vaccinated human sera and rabbit anti-Sabin II polyantibodies against a panel of iVDPV pseudoviruses. Results: The results demonstrated that the serum’s capacity to neutralize mutant pseudoviruses diminished when amino acid substitutions were introduced into the P1 encapsidated protein, particularly when 141 and 679 were mutated together. This study emphasizes the significance of continually monitoring individuals who are known to be immunocompromised and maintaining high vaccination rates in OPV-using communities.

Aspergillus flavipes L-methionine γ-lyase-β-cyclodextrin conjugates with improved stability, catalytic efficiency and anticancer activity.

Aspergillus flavipes L-methionine γ-lyase (MGL) has been authenticated as a powerful anticancer agent towards various solid tumors, however, the catalytic efficiency and stability of this enzyme remains the main challenge for its further in vivo applications. Thus, the objective of this study was to enhance the catalytic efficiency, structural stability of A. flavipes MGL, in addition to boost their anticancer activity, via conjugation with β-cyclodextrin. The purified A. flavipes MGL was (38.1μmol/mg/min) was conjugated with β-cyclodextrin, with immobilization yield 80%. The conjugation process of MGL with β-cyclodextrin was verified from the FTIR analysis, molecular docking analysis, ensuring the covalent conjugation process via the hydrogen, and hydrophobic interactions with the cyclodextrin hydroxyl groups and MGL surface amino acids residues. The free and CD-MGL have the same optimum reaction temperature 37°C, reaction pH 7.5 and pH stability pH 6.5-8.0. The CD-MGL conjugates had a significant stability to proteinase K and trypsin digestion. The affinity of CD-MGL was increased by ~ 2 folds to L-methionine (KM 3.1mM), compared to the free one (KM 7.2mM), as well as the catalytic efficiency of MGL was increased by 1.8 folds upon cyclodextrin conjugation. The higher affinity of CD-MGL for L-methionine might be due to re-orientation of the MGL to bind with the substrate by multiple interactions hydrogen, hydrophobic and covalent bonds compared to the free one. The thermal stability of MGL was increased by ~ 2 folds for the tested treatments, upon cyclodextrin conjugation. The in vitro anticancer activity of CD-MGL was enhanced by 2 folds against the HCT-116 (IC50 value 13.9μmol/mg/min) and MCF7 (IC50 value 9.6μmol/mg/min), compared to the free MGL (~ 21.4μmol/mg/min). The enzymes displayed a significant activity against the proliferation of Ehrlich ascites carcinoma in vivo, with an obvious improvement on the liver tissues, as revealed from the histopathological sections.

Study of Complex of AEDG Tetrapeptide with KRH Dendrimer at Two Different pH by Computer Simulation

In previous papers, we studied the behavior of lysine (Lys or K) based dendrimers of the second generation with repeating units KKK and KRR (i.e., with branched neutral lysine and charged double lysine or arginine (KK, RR) spacers). We also studied KLL, KAA, and KGG dendrimers with hydrophobic double leucine, alanine, and glycine (LL, AA, GG) spacers and pH-dependent KHH dendrimers with double histidine (HH) spacers. Their complexes with molecules of several medicinal peptides (including AEDG) were studied as well. It was shown that lysine dendrimers with charged spacers are suitable for the delivery of oppositely charged oligopeptides and genetic material, while dendrimers with hydrophobic internal spacers are good for the delivery of hydrophobic oligopeptides and fullerenes. In the present paper, we study complexes of molecules of AEDG peptide with KRH dendrimer containing arginine-histidine (RH) spacers. In this case, the amino acid residues in the spacer (R and H) of dendrimer are different, and the charge of the H residue depends on pH. We performed molecular dynamics simulations of the complexation of 16 AEDG molecules with a dendrimer at two different pHs: a) KRH at pH&gt;7 with fully uncharged histidines (H) and b) KRHp at pH&lt;5 with fully protonated (Hp) histidines in aqueous solution with explicit counterions. It was found that the dendrimer with protonated histidines forms a more compact complex. KRHp dendrimer can also carry more AEDG tetrapeptide molecules than KRH.

Tissue adaptation to metabolic stress: insights from SUMOylation

Post-translational modification (PTM) plays a crucial role in adaptation of mammals to environmental changes, enabling them to survive in stressful situations. One such PTM is SUMO modification, which is evolutionarily conserved. It involves the covalent and reversible attachment of a small ubiquitin-like modifier (SUMO) to lysine (Lys) residues in the target protein. SUMOylation regulates various functions, including cell proliferation, differentiation, apoptosis, senescence, and maintenance of specific cellular activities. It achieves this by influencing protein-protein interactions, subcellular localization, protein stability, and DNA binding activity. Mounting evidence suggests that SUMOylation is implicated in the pathogenesis of metabolic disorders such as obesity, insulin resistance, and fatty liver. This review aims to provide an overview of the role of SUMOylation in regulating tissue adaptation to metabolic stress. Recent advancements in spectroscopic techniques have shed light on potential targets of SUMOylation and the underlying regulatory mechanisms have been elucidated, laying the theoretical foundation for the development of targeted SUMOylation interventions for metabolic syndrome while minimizing side effects.

The influence of glycine on β-lactoglobulin amyloid fibril formation – computer simulation study

Abstract Amyloids are protein aggregates involved in various protein condensation diseases. Our study aims to investigate the influence of glycine on the fibrillization mechanism of β-lactoglobulin (BLG), a model protein known to form amyloid fibrils from hydrolysed peptides in low pH aqueous solutions. We conducted atomistic molecular dynamics simulations of aqueous solutions of native and unfolded BLG in glycine buffer at pH 2.0. During the simulations we put our focus on analysing protein-protein/buffer interactions, structural electrostatic potential mapping, and the residence times of glycine and glycinium near specific amino acid residues. Glycinium cations were found to preferentially interact with specific protein residues potentially masking the outer disulfide bonds, affecting thiol deprotonation and influencing disulfide scrambling equilibrium. These interactions can potentially hinder hydrolysis and change the fibrillization pathway. Further investigations, such as constant pH MD simulations, simulations on disulfide bounded oligomers are warranted to validate these findings and deepen our understanding of protein aggregation mechanisms.

An engineered Japanese encephalitis virus mRNA-lipid nanoparticle immunization induces protective immunity in mice

IntroductionJapanese encephalitis virus (JEV) and Zika virus (ZIKV) pose a severe threat to human health. Our previous research results, as well as those of other research groups, indicated that antibodies (Abs) induced by JEV infection or JEV vaccine vaccination could enhance ZIKV infection in vitro and exacerbate the mortality of ZIKV-infected mice, vice versa, which is known as antibody-dependent enhancement (ADE). Although studies on other flaviviruses revealed that altering the amino acid residues located in the fusion loop (FL) of envelope (E) protein can reduce the level of flavivirus-cross-reactive Abs, thereby abating the ADE of heterologous flavivirus infection, it is unclear whether this strategy is equally applicable to JEV.MethodsIn this study, we constructed recombinant adenoviruses and nucleotide-modified mRNA-lipid nanoparticle (LNP) encoding JEV wild-type E protein or E protein mutant (designated as Ad5-JEV-EWT and Ad5-JEV-Emut; JEV-EWT mRNA-LNP, and JEV-Emut mRNA-LNP). We evaluated the immunogenicity of these vaccine candidates in mice and the capacity of vaccine-immune mouse sera to neutralize JEV infection or mediate ADE of ZIKV infection in vitro and in vivo.ResultsAd5-JEV-Emut or JEV-Emut mRNA-LNP immunization induced ZIKV-cross-reactive Ab response which is dramatically lower than that induced by Ad5-JEV-EWT and JEV-EWT mRNA-LNP, respectively. The levels of JEV-neutralizing Abs induced by Ad5-JEV-Emut or JEV-Emut mRNA-LNP are comparable to that induced by Ad5-JEV-EWT and JEV-EWT mRNA-LNP, respectively. The ability of Abs induced by Ad5-JEV-Emut to enhance ZIKV infection in vitro is attenuated as compared with that induced by Ad5-JEV-EWT. Moreover, JEV-Emut mRNA-LNP immunization elicited potent T cell response similar to JEV-EWT mRNA-LNP in mice. Mice immunized with each mRNA-LNP exhibited lower level of serum viral load than the mock-immunized mice post JEV challenge. Mice receiving JEV-EWT mRNA-LNP-immune mouse sera exhibited ADE post ZIKV challenge whereas passively transferred JEV-Emut mRNA-LNP-immune mouse sera did not lead to obvious ADE of ZIKV infection in recipient mice. Most importantly, maternally acquired Abs did not enhance the mortality of 1-day-old neonates born to JEV-Emut mRNA-LNP-immunized mice post ZIKV challenge.DiscussionThese results suggest that optimizing the FL sequence of JEV could significantly reduce the level of JEV/ZIKV-cross-reactive Abs and abrogate the ADE of ZIKV infection, providing a promising strategy to develop effective and safety JEV vaccine.