Structure based innovative approach to analyze aptaprobe-GPC3 complexes in hepatocellular carcinoma.

BACKGROUND: Glypican-3 (GPC3), a membrane-bound heparan sulfate proteoglycan, is a biomarker of hepatocellular carcinoma (HCC) progression. Aptamers specifically binding to target biomolecules have recently emerged as clinical disease diagnosis targets. Here, we describe 3D structure-based aptaprobe platforms for detecting GPC3, such as aptablotting, aptaprobe-based sandwich assay (ALISA), and aptaprobe-based imaging analysis. RESULTS: For preparing the aptaprobe-GPC3 platforms, we obtained 12 high affinity aptamer candidates (GPC3_1 to GPC3_12) that specifically bind to target GPC3 molecules. Structure-based molecular interactions identified distinct aptatopic residues responsible for binding to the paratopic nucleotide sequences (nt-paratope) of GPC3 aptaprobes. Sandwichable and overlapped aptaprobes were selected through structural analysis. The aptaprobe specificity for using in HCC diagnostics were verified through Aptablotting and ALISA. Moreover, aptaprobe-based imaging showed that the binding property of GPC3_3 and their GPC3 specificity were maintained in HCC xenograft models, which may indicate a new HCC imaging diagnosis. CONCLUSION: Aptaprobe has the potential to be used as an affinity reagent to detect the target in vivo and in vitro diagnosing system.

Genomic and Proteomic Evidences for Exopolysaccharide Biosynthesis in Sphingobium chungbukense DJ77.

Sphingobium chungbukense DJ77 is a Gram-negative bacterium has metabolic capability of producing exopolysaccharide (EPS) as a potential reducing and stabilizing agent for metallic nanoparticle synthesis. In this study, we investigated the genomic and proteomic analysis to verify metabolic pathway and involved genes and enzymes related to EPS biosynthesis in S. chungbukense DJ77. End-sequencing results of randomly selected fosmid library, which were prepared from high molecular weight DNA of S. chungbukense DJ77, showed identity to sequences from genes related the EPS biosynthesis pathways in several bacteria. We also observed that proteomic responses in S. chungbukense DJ77 by heterogeneously expressing gelA and gelN involved in gellan biosynthesis in Sphingomonas elodea. Comparative two-dimensional gel electrophoresis revealed that both GelA and GelN altered internal expression levels of proteins involved in EPS biosynthesis in S. chungbukense DJ77. The results might provide the genomic and proteomic evidences for presence of EPS biosynthesis pathways in S. chungbukense DJ77.

Aptamer-Immobilized Surface Plasmon Resonance Biosensor for Rapid and Sensitive Determination of Virulence Determinant.

Shigella sonnei isolate invasion plasmid antigen protein, IpaH, was successfully expressed in recombinant overexpression bacterial system. The soluble expression IpaH was enhanced with molecular chaperon co-expressed environment. Specific aptamer IpaH17 was isolated through the SELEX process and showed fM binding affinity. IpaH17-SPR biosensor platform was involved to verify the binding sensitivity and specificity. The IpaH concentration dependent IpaH17-SPR sensor response was highly linear with a linear regression constant of 99.4% in the range between 0 and 100 ng/mL. In addition, S. sonnei revealed the specific RU value and detected in a real-time manner within 1 hour. Our study indicated that IpaH17-SPR sensor can allow for rapid, sensitive and specific determination of Shigella sonnei virulent factor.

Surface Plasmon Resonance Aptamer Biosensor for Discriminating Pathogenic Bacteria Vibrio parahaemolyticus.

In this paper, whole-bacteria SELEX (WB-SELEX) strategy was adopted to isolate specific aptamers against Vibrio parahaemolyticus. Round selection for V. parahaemolyticus was conducted 11 rounds, including two negative selection rounds. It was determined through real-time PCR amplification and post-SELEX experiment. The selected aptmers had high binding property and specificity to V. parahaemolyticus. Of 28 aptamers tested, VPCA-apta#1 had the highest binding affinity compared to other aptamer candidates obtained. To detect V. parahaemolyticus, aptamer based SPR biosensor platform was constructed and pathogenic bacteria sensing was conducted in two steps. The first step was to construct 5'-biotinylated VPCA-apta#1 binding probe. The second step was to incubate V. parahaemolyticus and test microbes in functionalized SA sensor chip in parallel. Our platform showed significant activity for detecting and discriminating V. parahaemolyticus from other enteric species such as Escherichia coli, Listeria monocytogenes, Sigella sonnei, and Vibrio fischeri. This is the first report on the use of whole-SELEX to isolate DNA aptamers specific for V. parahaemolyticus. We demonstrated the feasibility of using aptamer platform for the detection of V. parahaemolyticus in various food supplies. It might be used in multiple points of care for diagnosing Vibriosis.

Detecting and Discriminating Shigella sonnei Using an Aptamer-Based Fluorescent Biosensor Platform.

In this paper, a Whole-Bacteria SELEX (WB-SELEX) strategy was adopted to isolate specific aptamers against Shigella sonnei. Real-time PCR amplification and post-SELEX experiment revealed that the selected aptmers possessed a high binding affinity and specificity for S. sonnei. Of the 21 aptamers tested, the C(t) values of the SS-3 and SS-4 aptamers (Ct = 13.89 and Ct = 12.23, respectively) had the lowest value compared to other aptamer candidates. The SS-3 and SS-4 aptamers also displayed a binding affinity (KD) of 39.32 ± 5.02 nM and 15.89 ± 1.77 nM, respectively. An aptamer-based fluorescent biosensor assay was designed to detect and discriminate S. sonnei cells using a sandwich complex pair of SS-3 and SS-4. The detection of S. sonnei by the aptamer based fluorescent biosensor platform consisted of three elements: (1) 5'amine-SS-4 modification in a 96-well type microtiter plate surface (N-oxysuccinimide, NOS) as capture probes; (2) the incubation with S. sonnei and test microbes in functionalized 96 assay wells in parallel; (3) the readout of fluorescent activity using a Cy5-labeled SS-3 aptamer as the detector. Our platform showed a significant ability to detect and discriminate S. sonnei from other enteric species such as E. coli, Salmonella typhimurium and other Shigella species (S. flexneri, S. boydii). In this study, we demonstrated the feasibility of an aptamer sensor platform to detect S. sonnei in a variety of foods and pave the way for its use in diagnosing shigellosis through multiple, portable designs.

Enhanced lysosomal activity by overexpressed aminopeptidase Y in Saccharomyces cerevisiae.

Saccharomyces cerevisiae contains vacuoles corresponding to lysosomes in higher eukaryotes. Lysosomes are dynamic (not silent) organelles in which enzymes can be easily integrated or released when exposed to stressful conditions. Changes in lysosomal enzymes have been observed due to oxidative stress, resulting in an increased function of lysosomes. The protein profiles from H2O2- and NH4Cl-treated lysosomes showed different expression patterns, observed with two-dimensional gel electrophoresis. The aminopeptidase Y protein (APE3) that conspicuously enhanced antimicrobial activity than other proteins was selected for further studies. The S. cerevisiae APE3 gene was isolated and inserted into pYES2.0 expression vector. The GFP gene was inserted downstream to the APE3 gene for confirmation of APE3 targeting to lysosomes, and S. cerevisiae was transformed to pYES2::APE3::GFP. The APE3 did not enter in lysosomes and formed an inclusion body at 30 °C, but it inserted to lysosomes as shown by the merger of GFP with lysosomes at 28 °C. Antimicrobial activity of the cloned S. cerevisiae increased about 5 to 10 % against eight strains, compared to normal cells, and galactose induction is increased more two folds than that of normal cells. Therefore, S. cerevisiae was transformed to pYES2::APE3::GFP, accumulating a large amount of APE3, resulting in increased lysosomal activity. Increase in endogenous levels of lysosomes and their activity following genetic modification can lead to its use in applications such as antimicrobial agents and apoptosis-inducing materials for cancer cells, and consequently, it may also be possible to use the organelles for improving in vitro functions.

Color reduction of melanin by lysosomal and peroxisomal enzymes isolated from mammalian cells.

Lysosomes and peroxisomes are organelles with many functions in all eukaryotic cells. Lysosomes contain hydrolytic enzymes (lysozyme) that degrade molecules, whereas peroxisomes contain enzymes such as catalase that convert hydrogen peroxide (H2O2) to water and oxygen and neutralize toxicity. In contrast, melanin is known as a helpful element to protect the skin against harmful ultraviolet rays. However, a high quantity of melanin leads to hyperpigmentation or skin cancer in human. New materials have already been discovered to inhibit tyrosinase in melanogenesis; however, melanin reduction does not suggest their preparation. In this study, we report that the color intensity because of melanin decreased by the cellular activation of lysosomes and peroxisomes. An increase in the superficial intensity of lysosome and peroxisome activities of HeLa cells was observed. In addition, a decrease in the amount of melanin has also been observed in mammalian cells without using any other chemical, showing that the process can work in vivo for treating melanin. Therefore, the results of this study indicate that the amount of melanin decreases by the lysosome and peroxisome activity after entering the cells, and functional organelles are effective in color reduction. This mechanism can be used in vivo for treating melanin.

Effects of Alginate Oligosaccharide Mixture on the Bioavailability of Lysozyme as an Antimicrobial Agent.

In this study, we report an oral drug delivery system without any additional process using pH-sensitive biopolymer, alginate, and alginate oligosaccharide with lysozyme as a model drug. These biopolymers exhibited pH-sensitive characteristics such as shrinking at acidic pH and eroding with dissolution at alkaline pH. The incorporation of lysozyme and biopolymers was performed an artificial intestinal juice (pH 6.8). The immobilization efficiency and lysozyme stability in gastric juice (pH 1.2) has been tested by E coil antimicrobial activity. The lysozyme without biopolymer immobilization lost approximately 80-90% of antimicrobial activity than that of pure lysozyme. However, the pH-sensitive biopolymer-controlled lysozyme maintained similar antimicrobial activity compared to that of pure lysozyme (50-90% of cell mortality). Therefore, this simple, easy, and rapid system can be effectively and practically applied for pathogen treatment for in vivo oral drug delivery.

Antimicrobial Properties of Lysosomal Enzymes Immobilized on NH2Functionalized Silica-Encapsulated Magnetite Nanoparticles.

The immobilization efficiency, antimicrobial activity and recovery of lysosomal enzymes on NH2 functionalized magnetite nanoparticles have been studied under various conditions. The immobi- lization efficiency depends upon the ratio of the amount of enzyme and magnetite and it shows an increase with magnetite concentration which is due to the presence of amine group at the magnetite surface that leads to a strong attraction. The optimized reaction time to immobilize the lysosomal enzymes on magnetite was determined by using a rolling method. The immobilization efficiency increases with reaction time and reached a plateau after 5 minutes and then remained constant for 10 minutes. However, after 30 minutes the immobilization efficiency decreased to 85%, which is due to the weaker electrostatic interactions between magnetite and detached lysosomal enzymes. The recovery and stability of immobilized lysosomal enzymes has also been studied. The antimicrobial activity was almost 100% but it decreased upon reuse and no activity was observed after its reuse for seven times. The storage stability of lysosomal enzymes as an antimicrobial agent was about 88%, which decreased to 53% after one day and all activity of immobilized lysosomal enzymes was maintained after five days. Thus, the lysosomal enzymes immobilized on magnetite nanoparticles could potentially be used as antimicrobial agents to remove bacteria.

Enhanced Hydrogen Production by Co-cultures of Hydrogenase and Nitrogenase in Escherichia coli.

Rhodobacter sphaeroides is a bacterium that can produce hydrogen by interaction with hydrogenase and nitrogenase. We report a hydrogen production system using co-cultivation of hydrogenase in liquid medium and immobilized nitrogenase in Escherichia coli. The recombinant plasmid has been constructed to analyze the effect of hydrogen production on the expression of hupSL hydrogenase and nifHDK nitrogenase isolated from R. sphaeroides. All recombinant E. coli strains were cultured anaerobically, and cells for nitrogenase were immobilized in agar gel, whereas cells for hydrogenase were supplemented on the nitrogenase agar gel. The hupSL hydrogenase has been observed to enhance hydrogen production and hydrogenase activity under co-culture with nifHDK nitrogenase. The maximum hydrogen production has been obtained at an agar gel concentration and a cell concentration for co-culture of 2 % and 6.4 × 10(8) CFU. Thus, co-culture of hupSL hydrogenase and nifHDK nitrogenase provides a promising route for enhancing the hydrogen production and hydrogenase activity.

The effect of CbbR-binding affinity to the upstream of cbbF and cfxB on the metabolic effector in Rhodobacter sphaeroides.

Rhodobacter sphaeroides is a non-sulfur photosynthetic bacterium that possesses two cbb operons, cbb I and cbb II , encoding enzymes involved in the Calvin-Bensom-Bassham reductive pentose phosphate pathway of carbon dioxide fixation. In the present study, a number of molecules have been identified that have the ability to alter the in vivo DNA-binding properties of CbbR protein in R. sphaeroides. The CbbR-binding sites on the cbb operon in R. sphaeroides were characterized by chromatin immunoprecipitation (ChIP) assay. The ChIP assay indicated that the CbbR protein binds specifically to the upstream regions cbbF in cbb I operon and cfxB in cbb II operon. The change in the binding of CbbR to the upstream of cbbF and cfxB in the presence of RuBP, fructose 1,6-bisphosphate, NADPH, KH2PO4 was observed under anaerobic, aerobic, aerobic light-dark, and aerobic dark conditions, respectively. From these results, the role of different co-inducer molecules in influencing the interactions of CbbR with the binding site within cbb operon has been ascertained. The biosynthetic intermediates and other potential metabolic effectors have been observed to play an important role in the regulatory mechanism.

Structural and biochemical characterization of the cytosolic wheat cyclophilin TaCypA-1.

Cyclophilins belong to a family of proteins that bind to the immunosuppressive drug cyclosporin A (CsA). Several members of this protein family catalyze the cis-trans isomerization of peptide bonds preceding prolyl residues. The present study describes the biochemical and structural characteristics of a cytosolic cyclophilin (TaCypA-1) cloned from wheat (Triticum aestivum L.). Purified TaCypA-1 expressed in Escherichia coli showed peptidyl-prolyl cis-trans isomerase activity, which was inhibited by CsA with an inhibition constant of 78.3 nM. The specific activity and catalytic efficiency (kcat/Km) of the purified TaCypA-1 were 99.06 ± 0.13 nmol s(-1) mg(-1) and 2.32 × 10(5) M(-1) s(-1), respectively. The structures of apo TaCypA-1 and the TaCypA-1-CsA complex were determined at 1.25 and 1.20 Šresolution, respectively, using X-ray diffraction. Binding of CsA to the active site of TaCypA-1 did not result in any significant conformational change in the apo TaCypA-1 structure. This is consistent with the crystal structure of the human cyclophilin D-CsA complex reported at 0.96 Å resolution. The TaCypA-1 structure revealed the presence of a divergent loop of seven amino acids (48)KSGKPLH(54) which is a characteristic feature of plant cyclophilins. This study is the first to elucidate the structure of an enzymatically active plant cyclophilin which shows peptidyl-prolyl cis-trans isomerase activity and the presence of a divergent loop.

Modifications of mRNA vaccine structural elements for improving mRNA stability and translation efficiency.

BACKGROUND: mRNA vaccines hold great potential as therapeutic techniques against viral infections due to their efficacy, safety, and large-scale production. mRNA vaccines offer flexibility in development as any protein can be produced from mRNA without altering the production or application process. OBJECTIVE: This review highlights the iterative optimization of mRNA vaccine structural elements that impact the type, specificity, and intensity of immune responses leading to higher translational potency and intracellular stability. RESULTS: Modifying the mRNA structural elements particularly the 5' cap, 5'-and 3'-untranslated regions (UTRs), the coding region, and polyadenylation tail help reduce the excessive mRNA immunogenicity and consistently improve its intracellular stability and translational efficiency. CONCLUSION: Further studies regarding mRNA-structural elements and their optimization are needed to create new opportunities for engineering mRNA vaccines.

Cyclophilin A-mediated mitigation of coronavirus SARS-CoV-2.

Human cyclophilin A (hCypA) is important for the replication of multiple coronaviruses (CoVs), and cyclosporine A inhibitors can suppress CoVs. The emergence of rapidly spreading severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has sparked concerns that mutations affect the binding ability of the spike (S) protein to the angiotensin-converting enzyme 2 (ACE2) cell receptor, affecting the severity of coronavirus disease (COVID-19). Far-western blotting and surface plasmon resonance (SPR) results revealed that hCypA interacts strongly with the viral SARS-CoV-2 receptor-binding domain (RBD), with a binding affinity of 6.85 × 10-8 M. The molecular interaction between hCypA and the viral protein interface was shown using three-dimensional structural analysis, which revealed the blocking of key residues on the RBD interface by hCypA. The RBD facilitates binding to the ACE2 receptor. The hCypA-S protein complex suppressed the binding of RBD to the ACE2 receptor, which a required event for CoV entry into the host cell. The reliability of this postulated blocking mechanism of the hCypA-SARS-CoV2 RBD complex with ACE was confirmed by SPR and molecular interaction lateral flow (MILF) strip assay, which offers the immunochromatographic signal read-outs. The emergence of new SARS-CoV-2 variants with key mutations in RBD had a negligible effect on the binding of the RBD variants to hCypA, indicating an effective mitigation strategy for SARS-CoV-2 variants. The MILF strip assay results also highlight the neutralizing effect of hCypA by effectively blocking RBD (wild type and its variants) from binding ACE2. Given the importance of hCypA in viral entry regulation, it has the potential to be used as a target for antiviral therapy.

Effects of Light Regulation on Proteome Expression in Rhodobacter sphaeroides 2.4.1.

Light plays an important role in the transcriptional regulation of photosynthetic apparatus. The influence of oxygen and light conditions on the protein expression of Rhodobacter sphaeroides was investigated using a proteomic approach. The R. sphaeroides was grown aerobically under dark cultivation (D24) and light cultivation (L24) for 24 h. An average of 950 distinguishable spots were obtained on 2-D analytic gel for D24 and L24 conditions, of which 48 proteins exhibited significant changes in protein expression levels. Among the 48, 31 proteins were upregulated and 17 proteins were downregulated in L24 when compared with D24. The results depict the comparative protein expression in R. sphaeroides mediated through growth under light or dark conditions. The data suggest that the overexpressed proteins, phosphoribosyl-ATP pyrophosphatase (HisE), in the D24/aerobic culture are involved in the positive regulation of PAC production can be functionally applied in metabolic engineering and industrial processes.

The Response of Liposomes Modified with Lysosomal Membrane Proteins to the Targeting Ability Associated with Antimicrobial Activity.

Liposomes were modified using two different methods. In Method 1, liposomes were modified by mixing whole lysosomal proteins, lipid, and cholesterol before preparation. For Method 2, the liposomes were modified by mixing whole lysosomal proteins after liposome preparation. Method 1-modified liposomes exhibited improved cell mortality compared to Method 2-modified liposomes. The modified liposomes were then evaluated for their antimicrobial activity against lysosomal enzymes, and Escherichia coli did not modify the liposome surface. The whole lysosomal membrane proteins extracted from the lysosomes in Saccharomyces cerevisiae were analyzed using two-dimensional electrophoresis to find specific proteins associated with antimicrobial activity and to construct recombinant S. cerevisiae proteins. Additionally, genes related to antimicrobial activity were identified, and the liposomes modified by lysosomal membrane proteins of recombinant S. cerevisiae tagged with green fluorescence proteins were prepared and overexpressed. The modified liposomes exhibited improved antimicrobial activity with an almost two-fold increase in the cell mortality rate, suggesting crucial roles as potential therapeutics.

Aptamer-Based Paper Strip Sensor for Detecting Vibrio fischeri.

Aptamer-based paper strip sensor for detecting Vibrio fischeri was developed. Our method was based on the aptamer sandwich assay between whole live cells, V. fischeri and DNA aptamer probes. Following 9 rounds of Cell-SELEX and one of the negative-SELEX, V. fischeri Cell Aptamer (VFCA)-02 and -03 were isolated, with the former showing approximately 10-fold greater avidity (in the subnanomolar range) for the target cells when arrayed on a surface. The colorimetric response of a paper sensor based on VFCA-02 was linear in the range of 4 × 101 to 4 × 105 CFU/mL of target cell by using scanning reader. The linear regression correlation coefficient ( R2) was 0.9809. This system shows promise for use in aptamer-conjugated gold nanoparticle probes in paper strip format for in-field detection of marine bioindicating bacteria.

Molecular Docking Analysis and Biochemical Evaluation of Levansucrase from Sphingobium chungbukense DJ77.

Bacterial exopolymer Levan (ß-(2,6) polyfructan) synthesized by levansucrase has attracted interest for various applications due to its low intrinsic viscosity compared with other polysaccharides. We report a novel levansucrase (Lsc) isolated from Sphingobium chunbukense DJ77 and verify its biochemical characteristics by comparative analysis of molecular docking analysis (MOE) and catalytic residue analysis. The complete sequence of the Lsc encoding gene ( lsc) was cloned under the direction of the T7 promoter and purified in an Escherichia coli BL21 (DE3) protein expression system. The enzyme activity analysis and ligand docking MOE study of S. chungbukense DJ77 Lsc revealed that Arg 77, Ser112, Arg 195, Asp196, Glu257, and Gln275 were involved in the sucrose binding and splitting as well as transfructosylation activity. A catalytic comparison of Lsc of S. chungbukense DJ77 with the results of site-directed mutational analysis indicated that Gln275 may coordinate a favorable substrate binding environment, offering broad pH resistance in the range of 5-10. The results suggest that the recombinant E. coli carrying S. chungbukense DJ77 Lsc might produce levan under the regular growth conditions with less need for pH manipulation.

Aptamer-Based Pathogen Monitoring for Salmonella enterica ser. Typhimurium.

Salmonella enterica ser. Typhimurium is a foodborne pathogen that causes salmonellosis. Symptoms of salmonellosis include fever, diarrhea, and gastroenteritis. Conventional culture methods for detecting foodborne bacterial pathogens require long incubation time, expensive immunoassay methods, and sample enrichment steps. The objective of this study was to develop an aptamer-based sandwich assay to detect S. enterica ser. Typhimurium. First, S. enterica ser. Typhimurium specific binding aptamers (S11 and S24) were obtained by whole-cell SELEX for high sensitivity and specificity detection using live S. enterica ser. Typhimurium. S11 and S24 aptamers were able to capture S. enterica ser. Typhimurium selectively and distinguish it from other species of Salmonella (S. enterica ser. Typhimurium, S. enterica ser. Choleraesuis, S. enterica ser. Dublin, and S. enterica ser. Enteritidis) and food-borne bacterial pathogens (Escherichia coli K12, Listeria monocytogenes, Shigella sonnei and Staphylococcus aureus) with KD values of 4.41×10-12 M and 3.75×10-11 M, respectively. S. enterica ser. Typhimurium. aptamer-based sandwich assay exhibited a linear response for sensing S. enterica ser. Typhimurium. cells at concentration ranging from 2×101 to 2×105 CFU/mL. This aptamer-based sandwich assay can be used for on-site detection of S. enterica ser. Typhimurium.

Defining the copper binding aptamotif and aptamer integrated recovery platform (AIRP).

The potential copper binding sites in aptamers have been predicted on the basis of secondary structures and the binding affinity of aptamers with copper. Out of the 4 aptamers (Cu-A1 to Cu-A4) selected by SELEX and examined in the present study, the Cu-A2 aptamer shows the highest binding affinity to copper with the lowest KD value of 1.83 × 10-11 M. In order to confirm the binding of copper to the proposed region, the binding affinity was experimentally validated using mutation and deletion analysis. We have confirmed that the high G-C pairing patterns and short stem-interval distance play important roles in copper binding. Aptamer specificity was also verified against diverse heavy metals. We also demonstrate an Aptamer Integrated Recovery Platform (AIRP) to recover copper from acidic mine drainage. AIRP can be easily regenerated at least 20 times without significant deterioration of the retrieval performance. To the best of our knowledge, AIRP is the first demonstration of copper specific recovery using aptamers. This can be scaled up and would have diverse applications in metal contaminated water treatment, recovery and as a potential biosensor for environmental analysis, monitoring, and risk assessment.