RESUMO
Fibroblast growth factor (FGF) is a multifunctional protein that exhibits a wide range of biological effects. Most commonly, it acts as a mitogen, but it also has regulatory, morphological, and endocrine effects. The four receptor subtypes of FGF are activated by more than 20 different FGF ligands. FGF2, one of the FGF ligands, is an essential factor for cell culture in stem cells for regenerative medicine; however, recombinant FGF2 is extremely unstable. Here, we successfully generated homobivalent agonistic single-domain antibodies (variable domain of heavy chain of heavy chain antibodies referred to as VHHs) that bind to domain III and induce activation of the FGF receptor 1 and thus transduce intracellular signaling. This agonistic VHH has similar biological activity (EC50) as the natural FGF2 ligand. Furthermore, we determined that the agonistic VHH could support the proliferation of human-induced pluripotent stem cells (PSCs) and human mesenchymal stem cells, which are PSCs for regenerative medicine. In addition, the agonistic VHH could maintain the ability of mesenchymal stem cells to differentiate into adipocytes or osteocytes, indicating that it could maintain the properties of PSCs. These results suggest that the VHH agonist may function as an FGF2 mimetic in cell preparation of stem cells for regenerative medicine with better cost effectiveness.
Assuntos
Fator 2 de Crescimento de Fibroblastos , Domínios Proteicos , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos , Anticorpos de Domínio Único , Humanos , Adipócitos/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Fator 2 de Crescimento de Fibroblastos/metabolismo , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Ligantes , Mesoderma/citologia , Mesoderma/efeitos dos fármacos , Osteócitos/efeitos dos fármacos , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/agonistas , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/química , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Medicina Regenerativa , Transdução de Sinais/efeitos dos fármacos , Anticorpos de Domínio Único/metabolismo , Anticorpos de Domínio Único/farmacologiaRESUMO
Human transglutaminase 1 (TG1) modulates skin development, while its involvement in diseases remains poorly understood, necessitating comprehensive exploration of its substrate interactions. To study the substrate profile of TG1, an in vitro selection system based on cDNA display technology was used to screen two peptide libraries with mutations at varying distance from the reactive glutamine. Next-generation sequencing and bioinformatics analysis of the selected DNA pools revealed a detailed TG1 substrate profile, indicating preferred and non-preferred amino acid sequences. The peptide sequence, AEQHKLPSKWPF, was identified showing high reactivity and specificity to TG1. The position weight matrix calculated from the per amino acid enrichment factors was employed to search human proteins using an in-house algorithm, revealing six known TG1 substrate proteins with high scores, alongside a list of candidate substrates currently under investigation. Our findings are expected to assist in future medical diagnoses and development of treatments for skin disorders.
Assuntos
DNA Complementar , Sequenciamento de Nucleotídeos em Larga Escala , Transglutaminases , Humanos , Transglutaminases/genética , Transglutaminases/metabolismo , Especificidade por Substrato , DNA Complementar/genética , Sequência de Aminoácidos , Biblioteca de PeptídeosRESUMO
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the disease COVID-19 can lead to serious symptoms, such as severe pneumonia, in the elderly and those with underlying medical conditions. While vaccines are now available, they do not work for everyone and therapeutic drugs are still needed, particularly for treating life-threatening conditions. Here, we showed nasal delivery of a new, unmodified camelid single-domain antibody (VHH), termed K-874A, effectively inhibited SARS-CoV-2 titers in infected lungs of Syrian hamsters without causing weight loss and cytokine induction. In vitro studies demonstrated that K-874A neutralized SARS-CoV-2 in both VeroE6/TMPRSS2 and human lung-derived alveolar organoid cells. Unlike other drug candidates, K-874A blocks viral membrane fusion rather than viral attachment. Cryo-electron microscopy revealed K-874A bound between the receptor binding domain and N-terminal domain of the virus S protein. Further, infected cells treated with K-874A produced fewer virus progeny that were less infective. We propose that direct administration of K-874A to the lung could be a new treatment for preventing the reinfection of amplified virus in COVID-19 patients.
Assuntos
Anticorpos Antivirais/administração & dosagem , Antivirais/administração & dosagem , COVID-19 , Anticorpos de Domínio Único/administração & dosagem , Ligação Viral/efeitos dos fármacos , Administração Intranasal , Animais , Chlorocebus aethiops , Cricetinae , Modelos Animais de Doenças , Humanos , Mesocricetus , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/imunologia , Células VeroRESUMO
Gluten intolerance, or adverse intestinal reactions to gluten, is a fairly common problem among certain groups of people. Celiac disease is the most severe form of gluten intolerance, which can lead to permanent damage in the digestive system. Since lifelong avoidance of gluten is the only available treatment, development of reliable techniques to identify gluten contamination in food is important. Gliadin, a component of gluten, is known to play a major role in gluten toxicity. In this study, cDNA display method was used to select specific single-domain antibodies against toxic gliadin from an alpaca-derived naïve VHH library. The cDNA display method is a promising in vitro display technique, which uniquely converts an unstable mRNA-protein fusion molecule to a stable mRNA/cDNA-protein fusion molecule using a well-designed puromycin linker. Three candidate VHHs were selected and the affinities of the VHHs were observed by pulldown assay and indirect ELISA method. In addition, a novel cDNA display mediated immuno-PCR method (cD-IPCR) was successfully applied to detect gliadin in food. We believe this work demonstrates the potential application of the cDNA display method in selecting binders against toxic and heterogeneous targets such as gliadin with an immunization-free preparation manner.
Assuntos
Camelídeos Americanos/imunologia , Grão Comestível/química , Ensaio de Imunoadsorção Enzimática/métodos , Gliadina/análise , Cadeias Pesadas de Imunoglobulinas/imunologia , Reação em Cadeia da Polimerase/métodos , Anticorpos de Domínio Único/imunologia , Animais , Doença Celíaca/imunologia , Clonagem Molecular , DNA Complementar , Escherichia coli/genética , Biblioteca Gênica , Humanos , Hipersensibilidade a Trigo/imunologiaRESUMO
Binding peptides for given target molecules are often selected in vitro during drug discovery and chemical biology research. Among several display technologies for this purpose, complementary DNA (cDNA) display (a covalent complex of a peptide and its encoding cDNA linked via a specially designed puromycin-conjugated DNA) is unique in terms of library size, chemical stability, and flexibility of modification. However, selection of cDNA display libraries often suffers from false positives derived from non-specific binding. Although rigorous washing is a straightforward solution, this also leads to the loss of specific binders with moderate affinity because the interaction is non-covalent. To address this issue, herein, we propose a method to covalently link cDNA display molecules with their target proteins using light irradiation. We designed a new puromycin DNA linker that contains a photocrosslinking nucleic acid and prepared cDNA display molecules using the linker. Target proteins were also labeled with a short single-stranded DNA that should transiently hybridize with the linker. Upon ultraviolet (UV) light irradiation, cDNA display molecules encoding correct peptide aptamers made stable crosslinked products with the target proteins in solution, while display molecules encoding control peptides did not. Although further optimization and improvement is necessary, the results pave the way for efficient selection of peptide aptamers in multimolecular crowding biosystems.
Assuntos
Aptâmeros de Peptídeos/química , DNA Complementar/química , Peptídeos/química , Fotoquímica/métodosRESUMO
Immuno-PCR (IPCR) provides sensitive and versatile detection of a variety of antigens by conjugating a PCR-amplifiable DNA reporter to a specific antibody or an aptamer. Several methodologies have been developed to prepare appropriate DNA-antibody conjugates, but in most cases, it remains difficult to label polypeptides with high site-specificity and fixed stoichiometry. To address this issue, we first demonstrated the feasibility of IPCR based on cDNA display, a 1:1 covalent complex of a polypeptide and its encoding cDNA via puromycin at the single molecule level. Several other in vitro display technologies (e.g., ribosome display, mRNA display) have similar simple nucleic acid-peptide linkage. However, they should be unsuitable for diagnostic applications because of their lability against heat and RNase. The newly developed system here, termed cDNA display mediated immuno-PCR (cD-IPCR), proved to work in direct- and sandwich-type detection of target proteins. Detection of a target in serum was also possible, using a VHH (variable domain of the heavy chain of a heavy chain antibody) antibody as a binding molecule. Although further improvement on sensitivity and quantitativity is necessary before the method becomes useful, we believe this work demonstrated a potential of cD-IPCR as an alternative novel format of IPCR.
Assuntos
DNA Complementar/química , Ensaio de Imunoadsorção Enzimática/métodos , Proteína Estafilocócica A/química , Reação em Cadeia da Polimerase/métodos , Domínios e Motivos de Interação entre Proteínas , Anticorpos de Cadeia Única/químicaRESUMO
Single-domain antibodies (variable domain of the heavy chain of a heavy chain antibody; VHH) are promising reagents for therapeutics and diagnostics because of their stability, cost-effective production and material workability as a small antibody. Currently, general acquisition of a VHH using immunization of camelids is inconvenient from the standpoint of animal protection, cost and the process is time-consuming. Thus, a straightforward and efficient method for screening VHHs against a target molecule is required. In this study, we examined whether in vitro selection of a VHH against a target protein could be performed by a cDNA display method with an artificial VHH library that had the three complementarity-determining regions (CDRs) randomized by chemical synthesis. The results revealed that a particular VHH against survivin, which is a member of the inhibitor of apoptosis family, was selected with affinity in the range of 10-7 to 10-8â¯M. The in vitro selection of a VHH using cDNA display with an artificial synthesized library without animal immunization was shown to be effective for rapid and inexpensive screening of VHHs against a target protein.
Assuntos
DNA Complementar/genética , Anticorpos de Domínio Único/genética , Sequência de Aminoácidos , Animais , Brevibacillus/genética , DNA Complementar/imunologia , Biblioteca Gênica , Ligação Proteica , Anticorpos de Domínio Único/imunologia , Ressonância de Plasmônio de Superfície , Survivina/imunologiaRESUMO
Survivin, an inhibitor of the apoptosis protein family, is a potent tumor marker for diagnosis and prognosis. The enzyme-linked immunosorbent assay (ELISA) is one of the methods that has been used for detection of survivin. However, ELISA has several disadvantages caused by the use of conventional antibodies, and we have therefore been trying to develop a novel ELISA system using camelid single-domain antibodies (VHHs) as advantageous replacements. Here we report a supplemental approach to improve the VHH-polyclonal antibody sandwich ELISA for survivin detection. Iodoacetyl-functionalized pullulan was synthesized, and its thiol reactivity was characterized by a model reaction with l-cysteine. The thiophilic pullulan was applied to an immunoassay asan additive upon coating of standard assay plates with an anti-survivin VHH fusion protein with C-terminal cysteine. The results showed that the mole ratio of the additive to VHH had a significant effect on the consequent response. Mole ratios of 0.07, 0.7, and 7 led to 90% lower, 15% higher, and 69% lower responses, respectively, than the response of a positive control in which no additive was used. The background levels observed in any additive conditions were as low as that of a negative control lacking both VHH and the additive. These results indicate the applicability of the thiol-reactive pullulan as a response enhancer to VHH-based ELISA.
Assuntos
Anticorpos/imunologia , Ensaio de Imunoadsorção Enzimática , Glucanos/química , Proteínas Inibidoras de Apoptose/análise , Anticorpos de Domínio Único/imunologia , Animais , Anticorpos/química , Cisteína/química , Humanos , Ácido Iodoacético/química , Anticorpos de Domínio Único/química , SurvivinaRESUMO
O(6)-Methylguanine DNA methyltransferase (MGMT) cancels the anticancer effect of temozolomide (drug for glioblastoma), which introduces methylation to DNA. Therefore, developing an MGMT inhibitor is a promising strategy for the treatment of this cancer. For this purpose, a sensitive detection method that does not depend on the conventional radioisotope (RI) method was developed. This was realized by a fluorescence-based method that measured the amount of cleavable restriction sites demethylated by the action of MGMT; this method was enhanced by introducing a polymerase chain reaction (PCR) amplification step. As an assay of enzyme activity, 20-fold higher sensitivity (subnanomolar) was attained compared with our and others' fluorescence-based approaches.
Assuntos
Fluorescência , Glioblastoma/enzimologia , O(6)-Metilguanina-DNA Metiltransferase/análise , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Reação em Cadeia da Polimerase , Ativação Enzimática , Glioblastoma/metabolismo , Humanos , O(6)-Metilguanina-DNA Metiltransferase/genética , RadioisótoposRESUMO
G protein-coupled receptors (GPCRs) are major drug targets, and their ligands are currently being explored and developed by many pharmaceutical companies and independent researchers. Class A (rhodopsin-like) GPCRs compose a predominant GPCR family; therefore, class A GPCR ligands are in demand. Growth hormone secretagogue receptor (GHS-R) is a class A GPCR that stimulates food intake by binding to its peptide ligand, ghrelin. Therefore, antagonists of GHS-R are expected to exert antiobesity function. In this article, we describe the use of cDNA display to screen for successfully and identify an antagonistic peptide of GHS-R. The antagonistic peptide inhibited the ghrelin-induced increase in intracellular Ca(2+) in vitro (IC(50) = approximately 10 µM) and repressed the contraction of isolated animal stomach in response to ghrelin. Furthermore, peripheral administration of the peptide inhibited the food intake of mice. This work provides new insight into the development of antiobesity drugs and describes a method for the discovery of unique peptide ligands for class A GPCRs.
Assuntos
DNA Complementar/metabolismo , Receptores de Grelina/metabolismo , Animais , Fármacos Antiobesidade/farmacologia , Células CHO , Cálcio/química , Cálcio/metabolismo , Cricetinae , Cricetulus , Relação Dose-Resposta a Droga , Biblioteca Gênica , Grelina/metabolismo , Técnicas In Vitro , Concentração Inibidora 50 , Ligantes , Masculino , Camundongos , Modelos Biológicos , Peptídeos/química , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/metabolismoRESUMO
BACKGROUND: Even in the age of next-generation sequencing (NGS), it has been unclear whether or not cells within a single organism have systematically distinctive genomes. Resolving this question, one of the most basic biological problems associated with DNA mutation rates, can assist efforts to elucidate essential mechanisms of cancer. RESULTS: Using genome profiling (GP), we detected considerable systematic variation in genome sequences among cells in individual woody plants. The degree of genome sequence difference (genomic distance) varied systematically from the bottom to the top of the plant, such that the greatest divergence was observed between leaf genomes from uppermost branches and the remainder of the tree. This systematic variation was observed within both Yoshino cherry and Japanese beech trees. CONCLUSIONS: As measured by GP, the genomic distance between two cells within an individual organism was non-negligible, and was correlated with physical distance (i.e., branch-to-branch distance). This phenomenon was assumed to be the result of accumulation of mutations from each cell division, implying that the degree of divergence is proportional to the number of generations separating the two cells.
Assuntos
Fagus/genética , Genoma de Planta , Prunus/genética , Análise de Sequência de DNA , Sequência de Bases , Análise por Conglomerados , Metilação de DNA , DNA de Plantas/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Dados de Sequência Molecular , Folhas de Planta/genéticaRESUMO
Immobilization of a protein in a functionally active form and correct orientation for high-throughput analysis is crucial for surface-based protein-molecular interaction studies and should aid progress in associated nanotechnologies. Here, we present a general method for controlled and oriented immobilization of proteins by a puromycin-linker for cDNA display technology. The utility and potential of this method was demonstrated by examining the interaction between the B domain of protein A and immunoglobulin G (IgG) by surface plasmon resonance. This study revealed that the mRNA fragment of the mRNA-protein fusion (i.e., mRNA display) interferes with the interaction between the protein (B domain) and its target molecule (IgG). This results in a reduction of the apparent affinity by ~10-fold. This method is expected to find wide appeal in the fields of surface-based studies of protein-protein interactions, drug screening, and single molecule analysis that require only a small amount of protein sample.
Assuntos
Biotina/química , Imunoglobulina G/química , Puromicina/química , Proteína Estafilocócica A/química , Ressonância de Plasmônio de Superfície , Biotina/metabolismo , Biotinilação , Sistema Livre de Células , Proteínas Imobilizadas/química , Proteínas Imobilizadas/metabolismo , Imunoglobulina G/metabolismo , Biossíntese de Proteínas , Domínios e Motivos de Interação entre Proteínas , Estrutura Terciária de Proteína , Técnicas de Microbalança de Cristal de Quartzo , RNA Mensageiro/química , RNA Mensageiro/metabolismo , Proteína Estafilocócica A/metabolismoRESUMO
BACKGROUND: With the accelerating development of bioscience, the problem of research cost has become important. We previously devised and developed a novel concept microarray with manageable volumes (MMV) using a soft gel. It demonstrated the great potential of the MMV technology with the examples of 1024-parallel-cell culture and PCR experiments. However, its full potential failed to be expressed, owing to the nature of the material used for the MMV chip. RESULTS: In the present study, by developing plastic-based MMVs and associated technologies, we introduced novel technologies such as C2D2P (in which the cells in each well are converted from DNA to protein in 1024-parallel), NGS-non-dependent microbiome analysis, and other powerful applications. CONCLUSIONS: The reborn MMV-microarray technology has proven to be highly efficient and cost-effective (with approximately 100-fold cost reduction) and enables us to realize hitherto unattainable technologies.
Assuntos
Análise em Microsséries/instrumentação , Análise em Microsséries/métodos , Microbiota , Análise em Microsséries/economia , Reação em Cadeia da Polimerase , Reprodutibilidade dos TestesRESUMO
BACKGROUND: The isothermal amplification of RNA in vitro has been used for the study of in vitro evolution of RNA. Although Qß replicase has been traditionally used as an enzyme for this purpose, we planned to use norovirus replicase (NV3D(pol)) due to its structural simplicity in the scope of in vitro autonomous evolution of the protein. Characteristics of the enzyme NV3D(pol) in vitro were re-evaluated in this context. RESULTS: NV3D(pol), synthesized by using a cell-free translation system, represented the activities which were reported in the previous several studies and the reports were not fully consistent each other. The efficiency of the initiation of replication was dependent on the 3'-terminal structure of single-stranded RNA template, and especially, NV3D(pol) preferred a self-priming small stem-loop. In the non-self-priming and primer-independent replication reaction, the presence of -CCC residues at the 3'-terminus increased the initiation efficiency and we demonstrated the one-pot isothermal RNA (even dsRNA) amplification by 16-fold. NV3D(pol) also showed a weak activity of elongation-reaction from a long primer. Based on these results, we present a scheme of the primer-independent isothermal amplification of RNA with NV3D(pol) in vitro. CONCLUSIONS: NV3D(pol) can be used as an RNA replicase in in vitro RNA + protein evolution with the RNA of special terminal sequences.
Assuntos
Norovirus/enzimologia , Técnicas de Amplificação de Ácido Nucleico , RNA Polimerase Dependente de RNA/genética , Sequência de Aminoácidos , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Q beta Replicase/genética , Q beta Replicase/metabolismo , RNA/genética , RNA de Cadeia Dupla/genética , RNA Viral/genética , RNA Polimerase Dependente de RNA/metabolismoRESUMO
BACKGROUND: The library size is critical for selection in evolutionary molecular engineering (directed evolution). Although cDNA display has become a promising in vitro display technology by overcoming the instability of mRNA display, it is hindered by low yields. In this study, we improved the yield of cDNA display molecules by carefully examining each step of the preparation process. FINDINGS: We found that steric hindrance of ribosomes binding to the mRNA-protein fusion molecules was interfering with biotin-streptavidin binding. Additionally, reducing buffer exchange by performing RNase digestion in the His-tag-binding buffer to release the cDNA display molecules improved their His-tag purification. CONCLUSION: Our optimized conditions have improved the yield of cDNA display molecules by more than 10 times over currently used methods, making cDNA display more practically available in evolutionary molecular engineering.
RESUMO
In this paper, we demonstrate a novel pull-down method that dramatically reduces the cost and preparation time of a bait protein by cell-free translation with a puromycin linker. With the C-terminus of the bait protein linked to biotin through a puromycin molecule after the translation reaction and subsequent mRNA degradation by RNase, the prey protein was easily pulled down by streptavidin-coated magnetic beads in a test tube. Three fluorescent prey protein types were tested and confirmed by gel electrophoresis to be pulled down easily and rapidly, depending on their affinity.
Assuntos
Biotina/metabolismo , Mapeamento de Interação de Proteínas , Proteínas/metabolismo , Puromicina/química , Biotina/química , Sistema Livre de Células , Fluoresceína/química , Magnetismo , Ligação Proteica , Biossíntese de Proteínas , Proteínas/química , RNA Mensageiro/metabolismo , Estreptavidina/químicaRESUMO
BACKGROUND: Dentinogenic ghost cell tumor is a rare benign tumor that accounts for less than 3% of all cases and consists of the stellate reticulum, which is made up of enamel epithelioid and basaloid cells. Although DGCT is a benign tumor, the local infiltration of the odontogenic epithelium or recurrences have been reported, and its detailed pathology and treatments remain unclear. CASE PRESENTATION: This report describes the case of a 60-year-old Japanese male diagnosed with a maxillary dentinogenic ghost cell tumor. Images showed well-circumscribed, multilocular cystic lesions with a calcified substance in the interior. Marsupialization was performed along with biopsy to prevent the expansion of the lesion, and a partial maxillectomy was performed 2 years after the initial examination. Histopathological findings showed ameloblastomatous proliferation containing clusters of ghost cells and dentinoid materials, resulting in the diagnosis of dentinogenic ghost cell tumor. This article also reviews recently reported cases of dentinogenic ghost cell tumor. CONCLUSION: It is important to perform marsupialization, proper resection, and postoperative follow-up because of possible recurrence.
Assuntos
Ameloblastoma , Tumores Odontogênicos , Humanos , Masculino , Pessoa de Meia-Idade , Tumores Odontogênicos/diagnóstico por imagem , Tumores Odontogênicos/cirurgia , Maxila , Biópsia , Ameloblastoma/diagnóstico por imagem , Ameloblastoma/cirurgia , Diagnóstico DiferencialRESUMO
Several engineered protein scaffolds have been developed recently to circumvent particular disadvantages of antibodies such as their large size and complex composition, low stability, and high production costs. We previously identified peptide aptamers containing one or two disulfide-bonds as an alternative ligand to the interleukin-6 receptor (IL-6R). Peptide aptamers (32 amino acids in length) were screened from a random peptide library by in vitro peptide selection using the evolutionary molecular engineering method "cDNA display". In this report, the antagonistic activity of the peptide aptamers were examined by an in vitro competition enzyme-linked immunosorbent assay (ELISA) and an IL-6-dependent cell proliferation assay. The results revealed that a disulfide-rich peptide aptamer inhibited IL-6-dependent cell proliferation with similar efficacy to an anti-IL-6R monoclonal antibody.
Assuntos
Aptâmeros de Peptídeos/farmacologia , Proliferação de Células/efeitos dos fármacos , Interleucina-6/antagonistas & inibidores , Aptâmeros de Peptídeos/química , Aptâmeros de Peptídeos/genética , Linhagem Celular Tumoral , Cisteína/química , Cistina/química , DNA Complementar/genética , Ensaios de Triagem em Larga Escala , Humanos , Dados de Sequência Molecular , Biblioteca de Peptídeos , Seleção GenéticaRESUMO
cDNA display is an in vitro display technology based on a covalent linkage between a protein and its corresponding mRNA/cDNA, widely used for the selection of proteins and peptides from large libraries (1012) in a high throughput manner, based on their binding affinity. Here, we developed a platform using cDNA display and next-generation sequencing (NGS) for rapid and comprehensive substrate profiling of transglutaminase 2 (TG2), an enzyme crosslinking glutamine and lysine residues in proteins. After screening and selection of the control peptide library randomized at the reactive glutamine, a combinatorial library of displayed peptides randomized at positions - 1, + 1, + 2, and + 3 from the reactive glutamine was screened followed by NGS and bioinformatic analysis, which indicated a strong preference of TG2 towards peptides with glutamine at position - 1 (Gln-Gln motif), and isoleucine or valine at position + 3. The highly enriched peptides indeed contained the indicated sequence and showed a higher reactivity as TG2 substrates than the peptide previously selected by phage display, thus representing the novel candidate peptide probes for TG2 research. Furthermore, the obtained information on substrate profiling can be used to identify potential TG2 protein targets. This platform will be further used for the substrate profiling of other TG isozymes, as well as for the selection and evolution of larger biomolecules.
Assuntos
Proteínas de Ligação ao GTP , Transglutaminases , Biologia Computacional , DNA Complementar , Proteínas de Ligação ao GTP/metabolismo , Glutamina/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Biblioteca de Peptídeos , Peptídeos/química , Proteína 2 Glutamina gama-Glutamiltransferase , Especificidade por Substrato , Transglutaminases/metabolismoRESUMO
A variable domain of heavy chain antibody (VHH) has different binding properties than conventional antibodies. Conventional antibodies prefer binding to the convex portion of the antigen, whereas VHHs prefer epitopes, such as crevices and clefts on the antigen. Therefore, developing candidates with the binding characteristics of camelid VHHs is important. Thus, To this end, a synthetic VHH library that reproduces the structural properties of camelid VHHs was constructed. First, the characteristics of VHHs were classified according to the paratope formation based on crystal structure analyses of the complex structures of VHHs and antigens. Then, we classified 330 complementarity-determining region 3 (CDR3) structures of VHHs from the Protein Data Bank (PDB) into three loop structures: Upright, Half-Roll, and Roll. Moreover, these structures depended on the number of amino acid residues within CDR3. Furthermore, in the Upright loops, several amino acid residues in the FR2 are involved in the paratope formation, along with CDR3, suggesting that the FR2 design in the synthetic library is important. A humanized synthetic VHH library, comprising two sub-libraries, Upright and Roll, was constructed and named PharmaLogical. A validation study confirmed that our PharmaLogical library reproduces VHHs with the characteristics of the paratope formation of the camelid VHHs, and shows good performance in VHH screening.