P53 Peptide Research Articles

Identification and validation of cross-reactivity of anti-Thailand orthohantavirus nucleocapsid peptides

A Thailand orthohantavirus (THAIV) is endemic in Southeast Asia. This assumption is supported by isolation of THAIV from local small mammals. Also, anti-orthohantavirus antibodies were detected in human serum. However, our understanding of THAIV cross-reactivity with antibodies against other orthohantaviruses remains largely unknown.We used the in-silico approach to identify the cross-reactive immunogenic peptides of THAIV. The immunogenicity of these peptides was tested using convalescent serum from patients infected with Puumala (PUUV), Hantaan (HNTV) and Dobrava (DOBV) orthohantaviruses.We identified three THAIV peptides reacting with orthohantavirus convalescent serum. P1 peptide was reactive with serum from patients infected with PUUV, HNTV and DOBV. These peptides were found to be non-allergenic. Molecular docking and population coverage analysis revealed the potential of selected peptides to interact with diverse HLA alleles worldwide.Our data indicate that THAIV peptides could be used to develop diagnostics for orthohantaviruses circulating in Southeast Asia.

Antimicrobial activity of α/β hybrid peptides incorporating tBu-β3,3Ac6c against methicillin-resistant Staphylococcus aureus.

The incorporation of β-amino acids into peptides is a promising approach to develop proteolytically stable therapeutic agents. Short α/β hybrid peptidescontaining tBu-β3,3Ac6cː H2N-Lys-tBu-β3,3Ac6c-PEA, P1; H2N-Orn-tBu-β3,3Ac6c-PEA, P2; H2N-Arg-tBu-β3,3Ac6c-PEA, P3; LA-Lys-tBu-β3,3Ac6c-PEA, P4; LA-Orn-tBu-β3,3Ac6c-PEA, P5; LA-Arg-tBu-β3,3Ac6c-PEA, P6; LAu-Lys-tBu-β3,3Ac6c-PEA, P7; LAu-Orn-tBu-β3,3Ac6c-PEA, P8; and LAu-Arg-tBu-β3,3Ac6c-PEA, P9 were prepared. The antimicrobial efficacies of all the peptides were evaluated against ESKAPE pathogens, along with a small panel of multi-drug resistant (MDR) clinical isolates of S. aureus. Among all the peptides, P4, P6, and P7 showed significant efficacies against P. aeruginosa, S. aureus, and MRSA with an MIC value ranging from 6.25 to 12.5 μM. Further, in vitro, anti-staphylococcal assessment with their antimicrobial synergy of the peptides P4, P6, and P7 was carried out against MRSA, due to its better efficacy. The peptides P6 and P7 exhibited MRSA biofilm inhibition of 70% and 77%, respectively, at 4×MIC concentration. At its MIC concentration, about 19% hemolysis was observed for P4, P6, and P7.

Recombinant Bacillus subtilis expressing functional peptide and its effect on blunt snout bream (Megalobrama amblycephala) in two state of stress

This study was conducted to investigate the effects of recombinant Bacillus subtilis CM66-P4' (secreting P4, which related to previous research in this laboratory) on the antioxidant capacity and immune function of blunt snout bream (Megalobrama amblycephala) through in vitro and in vivo experiment. The culture experiment was divided into 3 groups, including control group (CG, with no additional bacteria), original bacteria group (OBG, with 2×109 CFU/kg Bacillus subtilis CM66) and recombinant bacteria group (RBG, with 2×109 CFU/kg Bacillus subtilis CM66-P4'). After 8 weeks of feeding, a part of the fish were subjected to fishing stress, and the rest were subjected to starvation stress test. Blood samples were collected for the determination of immune and stress-related indexes. The hepatocytes were divided into control group (CG) and experiment group with P4 peptide (LTG and HTG). The cells were collected after starvation treatment and the expression of related genes was detected. The results showed as follows: compared with the CG group, the gene expressions of hepatocytic hsp60 and hsp70 in the LTG and HTG groups were significantly suppressed after 24 h starvation stress (P < 0.05). The content of MDA, the activities of AKP and ALT in OBG group were significantly changed after 30 days starvation (P < 0.05), while the indexes in RBG group had no significant change. The changes of plasma cortisol, malondialdehyde (MDA) and Immunoglobulin M (IgM) in CG and OBG groups were significantly changed at 4 h after fishing stress (P < 0.05), while the indexes in RBG group was not. In conclusion, this study confirmed that Bacillus subtilis CM66-P4' has great potential in preventing adverse effects of stress on aquatic livestock.

Antifungal Efficacy of Ultrashort β-Peptides against Candida Species: Mechanistic Understanding and Therapeutic Implications.

Candidiasis, a condition spurred by the unchecked proliferation of Candida species, poses a formidable global health threat, particularly in immunocompromised individuals. The emergence of drug-resistant strains complicates management strategies, necessitating novel therapeutic avenues. Antimicrobial peptides (AMPs) have garnered attention for their potent antifungal properties and broad-spectrum activity against Candida species. This study assessed the antifungal effectiveness of ultrashort β-peptides against Candida strains, with a specific focus on peptide P3 (LAU-β3,3-Pip-β2,2-Ac6c-PEA). Our findings showed P3's remarkable fungistatic and fungicidal activities against Candida albicans, exhibiting an MIC of 4 μg/mL, comparable to those of standard antifungal drugs. The MIC value remained unchanged in the presence of ADC and BSA, indicating that serum albumin does not diminish the activity of P3. P3 demonstrates synergistic effects when combined with Fluconazole (FLU), Itraconazole (ITR), and Nystatin (NYS) to the extent that it becomes effective at 0.125, 0.125, and 0.03125 μg/mL, respectively. Concentration versus time-kill kinetics showed its time-dependent activity up to the first 12 h against C. albicans, and later concentration also played a role; indeed, at 24 h the whole culture was sterilized at 8× MIC. Post-antifungal effect assays confirmed prolonged suppression of pathogen growth after the removal of P3 from the media for significant durations. More importantly, P3 inhibits hyphae formation and biofilm development of Candida, outperforming Fluconazole with respect to these properties. Mechanistic insights display P3's potential to disrupt fungal cell membrane integrity and dose-dependent inhibition of ergosterol biosynthesis, essential for fungal cell wall integrity. Using the Bradford assay, it was observed that extracellular protein concentrations increased with higher doses of the compound, thereby validating the effect of P3 on membrane integrity. A comparative gene analysis using RT-PCR showed that P3 downregulates ERG3, ERG11, and HWP1, which are crucial for the survival and pathogenicity of C. albicans. The impact of P3 on ERG11 and ERG3 is more effective than that of Fluconazole. Molecular docking studies revealed strong binding of P3 to various isoforms of lanosterol 14-α-demethylase, a key enzyme in ergosterol synthesis. Furthermore, molecular dynamic simulations validated the stability of the most promising docking complex. Overall, our findings underscore P3's potential as a leading candidate for the development of innovative antifungal therapies, warranting further investigation and optimization.

FANCA promotes lung adenocarcinoma progression and is a potential target for epitope vaccine immunotherapy

BackgroundFANCA mutations have been detected in a variety of cancers and found to be pro-carcinogenic. However, no functional studies have been identified regarding the involvement of FANCA in the occurrence and the immune response of LUAD.MethodsThe mRNA expression and overall survival rates of FANCA were evaluated by the TIMER, PrognoScan and TCGA database in LUAD tissues, and FANCA expression was further validated by clinical serum samples using ELISA. The correlation between FANCA and immune infiltration level was investigated via TISIDB database and CIBERSORT algorithm. The Kaplan–Meier plotter was used to further evaluate the prognostic value based on the expression levels of FANCA in related immune cells. Then, the influence of FANCA knockout on the proliferation, migration, and invasion of A549 and H1299 cells was validated using CCK8, cloning formation, and Transwell assays. Subsequently, HLA-A2-restricted FANCA antigenic peptides were predicted and synthesized by NetMHC4.0 and SYFPEITHI, and DCs were induced and cultured in vitro. Finally, DCs loaded with HLA-A2-restricted FANCA antigenic peptides were co-cultured with autologous peripheral blood lymphocyte to generate specific CTLs. The killing effects of different CTLs on LUAD cells were studied.ResultsThe results showed that high levels of FANCA in patients with LUAD were significantly correlated with worse OS survival, which was correlated with age, clinical stage, pathological T stage, M stage, and N stage in LUAD. Knockdown of FANCA in A549 and H1299 cells significantly inhibited proliferation, metastasis, and invasion in vitro. In addition, FANCA was significantly related to immune infiltrate, genomic alterations and TMB. FANCA expression infuenced the prognosis of LUAD patients by directly affecting immune cell infltration. Finally, HLA-A2-restricted FANCA antigenic peptides were synthesized. And FANCA 146–154 (SLLEFAQYL) antigenic peptide exhibit a stronger affinity for DCs, and induce CTLs to produce stronger targeted killing ability for LUAD cells at an effector-to-target ratio of 40:1.ConclusionThese results demonstrated that the elevation of FANCA promotes malignant phenotype of LUAD, and the potential peptide P2 (SLLEFAQYL) derived from FANCA may be used as an epitope vaccine for the treatment of LUAD.

Oral administration of PIISVYWK and FSVVPSPK peptides attenuates obesity, oxidative stress, and inflammation in high fat diet-induced obese mice

The bioactive peptides PIISVYWK (P1) and FSVVPSPK (P2), derived from the blue mussel Mytilus edulis, exhibit significant benefits in combating obesity, oxidative stress, and inflammation. This study demonstrates that these peptides inhibit the differentiation of bone marrow-derived mesenchymal stem cells (BMMSCs) into adipocytes by downregulating the adipogenic transcription factors peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP-1). Furthermore, P1 and P2 reduce lipogenesis and enhance lipolysis through the activation of AMP-activated protein kinase (AMPK) and hormone-sensitive lipase (HSL). These peptides also decrease intracellular reactive oxygen species (ROS) generation during adipogenesis and inhibit the mitogen-activated protein kinase (MAPK) pathway, thereby reducing inflammation. The involvement of heme oxygenase-1 (HO-1) in this mechanism is confirmed by the reversal of these effects upon HO-1 inhibition. In vivo, oral administration of P1 and P2 in high-fat diet (HFD) obese mice prevents weight gain, reduces adipose tissue accumulation, lowers adipogenic and lipogenic biomarkers, improves serum cholesterol levels, enhances lipolysis, and decreases pro-inflammatory cytokine production. These findings suggest that P1 and P2 peptides may effectively prevent obesity and related metabolic disorders by activating the HO-1/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway.

Introducing Chemoselective Peptide Conjugation via N-Alkylation of Pyridyl-alanine: Solution and Solid Phase Applications.

A novel chemoselective peptide conjugation via late-stage N-alkylation of pyridyl-alanine (PAL) in the solution and solid phase, namely, NAP, is demonstrated. The method constructs functionally diverse and highly stable N-alkylated conjugates with various peptides. Notably, conjugations in the solid phase offered a more economical process. The method can provide the opportunity for dual labeling along with a cysteine handle in a peptide chain. Finally, we showcased that the antiproliferative activities of the p53 peptide (MDM2 inhibitor) could be 2-fold enhanced via NAP conjugation with the RGD peptide (selective integrin binder).

Identification of antimicrobial bioactive peptides from the camel milk protein lactoferrin: Molecular docking, molecular dynamic simulation, and in vitro study.

This study explores the potential of antimicrobial peptides (AMPs) derived from camel milk lactoferrin as novel agents against antibiotic-resistant pathogens. Through in silico screening and molecular dynamics simulations, seven lactoferrin-derived peptides were identified as potential AMPs, with peptides P1 and P33 showing promising inhibitory effects against methicillin-resistant Staphylococcus aureus (MRSA). In vitro assays confirmed the efficacy of P33 against pathogenic strains, notably exhibiting activity against multi-drug-resistant strains. Moreover, the lactoferrin-derived peptide P33 demonstrated relatively low cytotoxicity on human fibroblast cells. These findings suggest that P33 holds significant potential as an antimicrobial agent, particularly against antibiotic-resistant bacteria, warranting further in vivo investigations for efficacy and safety. This study highlights the importance of exploring alternative sources of antimicrobial peptides, such as camel milk lactoferrin, in combating the growing threat of antibiotic resistance.

Mechanisms of peptide agonist dissociation and deactivation of adhesion G-protein-coupled receptors.

Adhesion G protein-coupled receptors (ADGRs) belong to Class B2 of GPCRs and are involved in a wide array of important physiological processes. ADGRs contain a GPCR autoproteolysis-inducing (GAIN) domain that is proximal to the receptor N-terminus and undergoes autoproteolysis during biosynthesis to generate two fragments: the N-terminal fragment (NTF) and C-terminal fragment (CTF). Dissociation of NTF reveals a tethered agonist to activate CTF of ADGRs for G protein signaling. Synthetic peptides that mimic the tethered agonist can also activate the ADGRs. However, mechanisms of peptide agonist dissociation and deactivation of ADGRs remain poorly understood. In this study, we have performed all-atom enhanced sampling simulations using a novel Protein-Protein Interaction-Gaussian accelerated Molecular Dynamics (PPI-GaMD) method on the ADGRG2-IP15 and ADGRG1-P7 complexes. The PPI-GaMD simulations captured dissociation of the IP15 and P7 peptide agonists from their target receptors. We were able to identify important low-energy conformations of ADGRG2 and ADGRG1 in the active, intermediate, and inactive states, as well as exploring different states of the peptide agonists IP15 and P7 during dissociation. Therefore, our PPI-GaMD simulations have revealed dynamic mechanisms of peptide agonist dissociation and deactivation of ADGRG1 and ADGRG2, which will facilitate rational design of peptide regulators of the two receptors and other ADGRs.

Selective Clearance of Circulating Histones Based on Dodecapeptide-Grafted Copolymer Material for Sepsis Blood Purification.

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Research indicates that circulating histones, as pathogenic factors, may represent a therapeutic target for sepsis. However, effectively clearing circulating histones poses a challenge due to their structural similarity to normal blood proteins, their low abundance in the bloodstream, and serious interference from other blood biomacromolecules. Here we design a dodecapeptide-based functional polymer that can selectively adsorb circulating histones from the blood. The peptide, named P1 (HNHHQLALVESY), was discovered through phage display screening and demonstrated a strong affinity for circulating histones while exhibiting negligible affinities for common proteins in the blood, such as human serum albumin (HSA), immunoglobulin G (IgG), and transferrin (TRF). Furthermore, the P1 peptide was incorporated into a functional polymer design, poly(PEGMA-co-P1), which was immobilized onto a silica gel surface through reversible addition-fragmentation chain transfer polymerization. The resulting material was characterized using solid nuclear magnetic resonance, thermogravimetric analysis, and X-ray photoelectron spectroscopy. This material demonstrated the ability to selectively and efficiently capture circulating histones from both model solutions and whole blood samples while also exhibiting satisfactory blood compatibility, good antifouling properties, and resistance to interference. Satisfactory binding affinity and efficient capture capacity toward histone were also observed for the other screened peptide P2 (QMSMDLFGSNFV)-grafted polymer, validating phage display as a reliable ligand screening strategy. These findings present an approach for the specific clearance of circulating histones and hold promise for future clinical applications in blood purification toward sepsis.

Machine Learning-Driven Discovery and Evaluation of Antimicrobial Peptides from Crassostrea gigas Mucus Proteome.

Marine antimicrobial peptides (AMPs) represent a promising source for combating infections, especially against antibiotic-resistant pathogens and traditionally challenging infections. However, traditional drug discovery methods face challenges such as time-consuming processes and high costs. Therefore, leveraging machine learning techniques to expedite the discovery of marine AMPs holds significant promise. Our study applies machine learning to develop marine AMPs, focusing on Crassostrea gigas mucus rich in antimicrobial components. We conducted proteome sequencing of C. gigas mucous proteins, used the iAMPCN model for peptide activity prediction, and evaluated the antimicrobial, hemolytic, and cytotoxic capabilities of six peptides. Proteomic analysis identified 4490 proteins, yielding about 43,000 peptides (8-50 amino acids). Peptide ranking based on length, hydrophobicity, and charge assessed antimicrobial potential, predicting 23 biological activities. Six peptides, distinguished by their high relative scores and promising biological activities, were chosen for bactericidal assay. Peptides P1 to P4 showed antimicrobial activity against E. coli, with P2 and P4 being particularly effective. All peptides inhibited S. aureus growth. P2 and P4 also exhibited significant anti-V. parahaemolyticus effects, while P1 and P3 were non-cytotoxic to HEK293T cells at detectable concentrations. Minimal hemolytic activity was observed for all peptides even at high concentrations. This study highlights the potent antimicrobial properties of naturally occurring oyster mucus peptides, emphasizing their low cytotoxicity and lack of hemolytic effects. Machine learning accurately predicted biological activity, showcasing its potential in peptide drug discovery.

A novel antifungal peptide, SP1.2, from Rhodopseudomonas palustris against the rice blast pathogen.

Rice blast has a significant detrimental impact on rice yields, so developing efficient biological control technologies is an effective means for rice blast prevention and control. The GroEL protein has proven to be effective at preventing and managing the pathogenicity of rice blast. Here, we analyzed the amino acid sequence of the GroEL protein and synthesized the '60 kDa chaperonin signature' (350-373 amino acids) peptide SP1.2, which has potent antifungal activity. Notably, the SP1.2 peptide exhibited potent fungicidal activity against Magnaporthe oryzae, effectively inhibiting appressorium germination. Electron microscopy revealed that SP1.2 disrupted the fungal plasma membrane and bound to multiple bioactive phosphoinositides in vitro, triggering the production of reactive oxygen species. Furthermore, it also caused an increase in the acetylation of M. oryzae and induced autophagy in cells. The spray application of SP1.2 significantly reduced the number of disease spots caused by the fungal pathogen M. oryzae in rice, enhancing the defense response of rice plants. Field trials showed that the control effect was 64.59% after spraying SP1.2. Our study illustrates the antifungal activity of the structurally unique SP1.2 peptide against plant fungal pathogens and paves the way for the future development of this class of peptides as antifungal agents. © 2024 Society of Chemical Industry.

Cell Proliferation, Chondrogenic Differentiation, and Cartilaginous Tissue Formation in Recombinant Silk Fibroin with Basic Fibroblast Growth Factor Binding Peptide.

Regeneration of articular cartilage remains a challenge for patients who have undergone cartilage injury, osteochondritis dissecans and osteoarthritis. Here, we describe a new recombinant silk fibroin with basic fibroblast growth factor (bFGF) binding peptide, which has a genetically introduced sequence PLLQATLGGGS, named P7. In this study, we cultured a human mesenchymal cell line derived from bone marrow, UE6E7-16, in wild-type fibroin sponge (FS) and recombinant silk fibroin sponge with P7 peptide (P7 FS). We compared cell proliferation, chondrogenic differentiation and cartilaginous tissue formation between the two types of sponge. After stimulation with bFGF at 3 ng/mL, P7 FS showed significantly higher cell growth (1.2-fold) and higher cellular DNA content (5.6-fold) than did wild-type FS. To promote chondrogenic differentiation, cells were cultured in the presence of TGF-β at 10 ng/mL for 28 days. Immunostaining of P7 FS showed SOX9-positive cells comparable to wild-type FS. Alcian-Blue staining of P7 FS also showed cartilaginous tissue formation equivalent to wild-type FS. A significant increase in cell proliferation in P7 FS implies future clinical application of this transgenic fibroin for regeneration of articular cartilage. To produce cartilaginous tissue efficiently, transgenic fibroin sponges and culture conditions must be improved. Such changes should include the selection of growth factors involved in chondrogenic differentiation and cartilage formation.

Molecular Mechanism of P53 Peptide Permeation through Lipid Membranes from Solid-State NMR Spectroscopy and Molecular Dynamics Simulations.

Macrocyclic peptides show promise in targeting high-value therapeutically relevant binding sites due to their high affinity and specificity. However, their clinical application is often hindered by low membrane permeability, which limits their effectiveness against intracellular targets. Previous studies focused on peptide conformations in various solvents, leaving a gap in understanding their interactions with and translocation through lipid bilayers. Addressing this, our study explores the membrane interactions of stapled peptides, a subclass of macrocyclic peptides, using solid-state nuclear magnetic resonance (ssNMR) spectroscopy and molecular dynamics (MD) simulations. We conducted ssNMR measurements on ATSP-7041M, a prototypical stapled peptide, to understand its interaction with lipid membranes, leading to an MD-informed model for peptide membrane permeation. Our findings reveal that ATSP-7041M adopts a stable α-helical structure upon membrane binding, facilitated by a cation-π interaction between its phenylalanine side chain and the lipid headgroup. This interaction makes the membrane-bound state energetically favorable, facilitating membrane affinity and insertion. The bound peptide displayed asymmetric insertion depths, with the C-terminus penetrating deeper (approximately 9 Å) than the N-terminus (approximately 4.3 Å) relative to the lipid headgroups. Contrary to expectations, peptide dynamics was not hindered by membrane binding and exhibited rapid motions similar to cell-penetrating peptides. These dynamic interactions and peptide-lipid affinity appear to be crucial for membrane permeation. MD simulations indicated a thermodynamically stable transmembrane conformation of ATSP-7041M, reducing the energy barrier for translocation. Our study offers an in silico view of ATSP-7041M's translocation from the extracellular to the intracellular region, highlighting the significance of peptide-lipid interactions and dynamics in enabling peptide transit through membranes.

Reverse vaccinology approach for identification of epitopes from E1 protein as peptide vaccine against HCV: A proof of concept

The development of effective vaccines against Hepatitis C Virus (HCV) remains a global health priority and challenge. In this study, we employed an integrative approach combining computational epitope prediction with experimental validation to identify immunogenic peptides targeting the E1 glycoprotein of HCV. In the present report, computational data from various epitope prediction algorithms such as IEDB and SYFPEITHI, followed by molecular dynamics (MD) simulations and immuno-informatics analysis is presented. Through computational screening, we identified potential epitope candidates, with QVRNSSGLY (P3) and QLFTFSPRH (P7) emerging as promising candidates. MD simulations revealed stable interactions between these epitopes and MHC molecule, further validated by free energy estimations using MMPBSA method. Immuno-informatics analysis supported these findings, showing high binding potential and immunogenicity scores for the selected peptides. Subsequent synthesis and characterization of epitope peptides confirmed their structural integrity and purity required for conducting immune activation assays. Experimental immunological assays carried out in this study involved epitope peptide induced activation of CD8 + and CD4 + T cells from healthy human subjects and HCV- recovered patients. Data from experimental validation revealed significant cytokine release upon exposure to epitope peptides, particularly TNF-a, IL-6, and GM-CSF, indicative of robust immune responses. Notably, peptides P3 and P7 exhibited the most pronounced cytokine induction profiles, underscoring their potential as vaccine candidates. Further investigations addressing the mechanism of action of these epitope peptides under preclinical and clinical settings may help in developing effective vaccine against HCV.

Investigation of the Effect of Peptide p5 Targeting CDK5-p25 Hyperactivity on Munc18-1 (P67) Regulating Neuronal Exocytosis Using Molecular Simulations.

Munc18-1 is an SM (sec1/munc-like) family protein involved in vesicle fusion and neuronal exocytosis. Munc18-1 is known to regulate the exocytosis process by binding with closed- and open-state conformations of Syntaxin1, a protein belonging to the SNARE family established to be central to the exocytosis process. Our previous work studied peptide p5 as a promising drug candidate for CDK5-p25 complex, an Alzheimer's disease (AD) pathological target. Experimental in vivo and in vitro studies suggest that Munc18-1 promotes p5 to selectively inhibit the CDK5-p25 complex without affecting the endogenous CDK5 activity, a characteristic of remarkable therapeutic implications. In this paper, we identify several binding modes of p5 with Munc18-1 that could potentially affect the Munc18-1 binding with SNARE proteins and lead to off-target effects on neuronal communication using molecular dynamics simulations. Recent studies indicate that disruption of Munc18-1 function not only disrupts neurotransmitter release but also results in neurodegeneration, exhibiting clinical resemblance to other neurodegenerative conditions such as AD, causing diagnostic and treatment challenges. We characterize such interactions between p5 and Munc18-1, define the corresponding pharmacophores, and provide guidance for the in vitro validation of our findings to improve therapeutic efficacy and safety of p5.

A Potent Sybody Selectively Inhibits α-Synuclein Amyloid Formation by Binding to the P1 Region.

Increasing research efforts focus on exploiting antibodies to inhibit the amyloid formation of neurodegenerative proteins. Nevertheless, it is challenging to discover antibodies that inhibit this process in a specific manner. Using ribosome display, we screened for synthetic single-domain antibodies, i.e., sybodies, of the P1 region of α-synuclein (residues 36-42), a protein that forms amyloid in Parkinson's disease and multiple-system atrophy. Hits were assessed for direct binding to a P1 peptide and the inhibition of amyloid formation. We discovered a sybody, named αSP1, that inhibits amyloid formation of α-synuclein at substoichiometric concentrations in a specific manner, even within highly crowded heterogeneous mixtures. Fluorescence resonance energy transfer-based binding assays and seeding experiments with and without αSP1 further demonstrate the importance of the P1 region for both primary and secondary nucleation mechanisms of amyloid assembly.

Bio-inspired metal extraction: Tailoring peptides for highly selective scandium recovery

Scandium, a pivotal metal with widespread applications, faces challenges in recovery due to its highly dispersed distribution. Biological molecules such as proteins and peptides have shown great potential in the field of metal recovery due to their unparalleled affinity and remarkable selectivity. This research aims to design a scandium-binding peptide by mutating the amino acids and optimizing the structure of the EF-hand peptide derived from lanmodulin, a naturally lanthanides-binding protein. Utilizing computer-aided techniques, three peptides-P1 and its two variants (P2 and P3), were screened and synthesized to characterize their interaction with scandium and other competing metals through circular dichroism (CD), atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR) as well as column adsorption experiments. Results showed that the peptide P2 and P3 exhibited higher affinity to scandium than P1, as a result of the more binding sites and the existence of hydrogen bonds in the peptides. Moreover, scandium could induce the significant change in backbone structure of these peptides, and coordinated with carboxyl groups of aspartic acid and glutamic acid. The column adsorption experiments with immobilized peptide P3 on microbeads revealed that a final scandium purity of 96.71 % was achieved and a enrichment coefficient of > 103 was obtained. This study offers a transformative strategy for selective scandium extraction from complex industrial matrices and lays the foundation for future innovations in green extraction technologies.

Antibiotics-Induced Intestinal Immunomodulation Attenuates Experimental Autoimmune Neuritis (EAN)

BackgroundThe composition of gut microbiota plays a pivotal role in priming the immune system and thus impacts autoimmune diseases. Data on the effects of gut bacteria eradication via systemic antibiotics on immune neuropathies are currently lacking. This study therefore assessed the effects of antibiotics-induced gut microbiota alterations on the severity of experimental autoimmune neuritis (EAN), a rat model of Guillain-Barré Syndrome (GBS). Myelin P0 peptide 180–199 (P0 180–199)-induced EAN severity was compared between adult Lewis rats (12 weeks old) that received drinking water with or without antibiotics (colistin, metronidazole, vancomycin) and healthy rats, beginning antibiotics treatment immediately after immunization (day 0), and continuing treatment for 14 consecutive days. Neuropathy severity was assessed via a modified clinical score, and then related to gut microbiota alterations observed after fecal 16S rRNA gene sequencing at baseline and after EAN induction. Effectors of gut mucosal and endoneurial immunity were assessed via immunostaining. EAN rats showed increased gut mucosal permeability alongside increased mucosal CD8+ T cells compared to healthy controls. Antibiotics treatment alleviated clinical EAN severity and reduced endoneurial T cell infiltration, decreased gut mucosal CD8+ T cells and increased gut bacteria that may be associated with anti-inflammatory mechanisms, like Lactobacillus or Parasutterella. Our findings point out a relation between gut mucosal immunity and the pathogenesis of EAN, and indicate that antibiotics-induced intestinal immunomodulation might be a therapeutic approach to alleviate autoimmunity in immune neuropathies. Further studies are warranted to evaluate the clinical transferability of these findings to patients with GBS.Graphical

Structural Adaptation of Secondary p53 Binding Sites on MDM2 and MDMX

The thermodynamics of secondary p53 binding sites on MDM2 and MDMX were evaluated using p53 peptides containing residues 16–29, 17–35, and 1–73. All the peptides had large, negative heat capacity (ΔCp), consistent with the burial of p53 residues F19, W23, and L26 in the primary binding sites of MDM2 and MDMX. MDMX has a higher affinity and more negative ΔCp than MDM2 for p5317-35, which is due to MDMX stabilization and not additional interactions with the secondary binding site. ΔCp measurements show binding to the secondary site is inhibited by the disordered tails of MDM2 for WT p53 but not a more helical mutant where proline 27 is changed to alanine. This result is supported by all-atom molecular dynamics simulations showing that p53 residues 30–35 turn away from the disordered tails of MDM2 in P27A17-35 and make direct contact with this region in p5317-35. Molecular dynamics simulations also suggest that an intramolecular methionine-aromatic motif found in both MDM2 and MDMX structurally adapts to support multiple p53 binding modes with the secondary site. ΔCp measurements also show that tighter binding of the P27A mutant to MDM2 and MDMX is due to increased helicity, which reduces the energetic penalty associated with coupled folding and binding. Our results will facilitate the design of selective p53 inhibitors for MDM2 and MDMX.