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1.
Biochemistry (Mosc) ; 84(5): 520-528, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31234766

RESUMO

In our recent X-ray study, we demonstrated that substitution of the natural leucine residue M196 with histidine in the reaction center (RC) from Rhodobacter (Rba.) sphaeroides leads to formation of a close contact between the genetically introduced histidine and the primary electron donor P (bacteriochlorophylls (BChls) PA and PB dimer) creating a novel pigment-protein interaction that is not observed in native RCs. In the present work, the possible nature of this novel interaction and its effects on the electronic properties of P and the photochemical charge separation in isolated mutant RCs L(M196)H are investigated at room temperature using steady-state absorption spectroscopy, light-induced difference FTIR spectroscopy, and femtosecond transient absorption spectroscopy. The results are compared with the data obtained for the RCs from Rba. sphaeroides pseudo-wild type strain. It is shown that the L(M196)H mutation results in a decrease in intensity and broadening of the long-wavelength Qy absorption band of P at ~865 nm. Due to the mutation, there is also weakening of the electronic coupling between BChls in the radical cation P+ and increase in the positive charge localization on the PA molecule. Despite the significant perturbations of the electronic structure of P, the mutant RCs retain high electron transfer rates and quantum yield of the P+QA- state (QA is the primary quinone acceptor), which is close to the one observed in the native RCs. Comparison of our results with the literature data suggests that the imidazole group of histidine M196 forms a π-hydrogen bond with the π-electron system of the PB molecule in the P dimer. It is likely that the specific (T-shaped) spatial organization of the π-hydrogen interaction and its potential heterogeneity in relation to the bonding energy is, at least partially, the reason that this type of interaction between the protein and the pigment and quinone cofactors is not realized in the native RCs.


Assuntos
Proteínas de Bactérias/metabolismo , Histidina/metabolismo , Leucina/metabolismo , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Rhodobacter sphaeroides/metabolismo , Proteínas de Bactérias/genética , Cristalografia por Raios X , Transporte de Elétrons , Histidina/genética , Cinética , Leucina/genética , Mutagênese Sítio-Dirigida , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Estrutura Terciária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Biochemistry (Mosc) ; 84(5): 540-552, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31234768

RESUMO

L-Arabinose is an important component of mycobacterial cell wall. L-Arabinose is involved in the synthesis of arabinogalactan, lipoarabinomannan, and other sugar compounds, which suggests that it can modulate cell wall permeability and drug resistance. However, whether L-arabinose affects mycobacterial antibiotic resistance and the underlying regulatory mechanism remains unclear. In this study, we characterized a new transcription factor of Mycobacterium smegmatis, AraR, that responds to L-arabinose and regulates mycobacterial sensitivity to isoniazid (INH). AraR specifically recognizes two conserved 15-bp motifs within the upstream regulatory region of the arabinose (araR) operon. AraR functions as a transcriptional repressor that negatively regulates araR expression. In contrast to the effect of AraR, overexpression of the araR operon contributes to the mycobacterial INH resistance. L-arabinose acts as an effector and derepresses transcriptional inhibition by AraR. The araR-deficient strain is more resistant to INH than the wild-type strain, whereas the araR-overexpressing strain is more sensitive to INH. Addition of L-arabinose to the medium can significantly increase the resistance to INH of the wild-type strain, but not of the araR knockout strain. Therefore, we identified a new L-arabinose-responding transcription factor and revealed its effect on the bacterial antibiotic resistance. These findings can provide new insights in the regulatory mechanisms mediated by sugar molecules and their relationship with drug resistance in mycobacteria.


Assuntos
Antituberculosos/farmacologia , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana/efeitos dos fármacos , Isoniazida/farmacologia , Mycobacterium smegmatis/metabolismo , Fatores de Transcrição/metabolismo , Arabinose/química , Arabinose/metabolismo , Proteínas de Bactérias/genética , Sequência de Bases , Mycobacterium smegmatis/efeitos dos fármacos , Óperon , Ligação Proteica , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Fatores de Transcrição/genética
3.
Biochemistry (Mosc) ; 84(4): 390-397, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31228930

RESUMO

Recombinant malic enzyme from the aerobic methanotroph Methylosinus trichosporium was obtained by heterologous expression in Escherichia coli and purified by affinity metal-chelating chromatography. The homohexameric enzyme of 6×80 kDa catalyzed the reversible reaction of oxidative decarboxylation of malate to pyruvate in the presence of mono- and divalent cations and NADP+ as a cofactor. The kcat/Km ratio indicated much higher catalytic efficiency of the malate decarboxylation reaction as compared with the pyruvate carboxylation reaction. Analysis of the protein sequence revealed that the C-region of the enzyme contains a large domain homologous to phosphoacetyltransferase, but no phosphoacetyltransferase activity was detected either for a full chimeric malic enzyme or for the C-end fragment obtained as a separate protein. This C-end domain promoted activity of the malic enzyme.


Assuntos
Malato Desidrogenase/metabolismo , Methylosinus trichosporium/enzimologia , Biocatálise , Descarboxilação , Cinética , Malato Desidrogenase/química , Malato Desidrogenase/genética , NADP/metabolismo , Ácido Pirúvico/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação
4.
Biochemistry (Mosc) ; 84(4): 426-434, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31228934

RESUMO

The bacterium Escherichia coli has seven σ subunits that bind core RNA polymerase and are necessary for promoter recognition. It was previously shown that the σ70 and σ38 subunits can also interact with the transcription elongation complex (TEC) and stimulate pausing by recognizing DNA sequences similar to the -10 element of promoters. In this study, we analyzed the ability of the σ32, σ28, and σ24 subunits to induce pauses in reconstituted TECs containing corresponding -10 consensus elements. It was found that the σ24 subunit can induce a transcriptional pause depending on the presence of the -10 element. Pause formation is suppressed by the Gre factors, suggesting that the paused complex adopts a backtracked conformation. Some natural promoters contain potential signals of σ24-dependent pauses in the initially transcribed regions, suggesting that such pauses may have regulatory functions in transcription.


Assuntos
RNA Polimerases Dirigidas por DNA/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Transcrição Genética/fisiologia , Sequência de Bases , DNA/metabolismo , RNA Polimerases Dirigidas por DNA/genética , Proteínas de Escherichia coli/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Fator sigma/genética , Fator sigma/metabolismo , Fatores de Transcrição/metabolismo
5.
Cell Physiol Biochem ; 53(1): 87-100, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31204440

RESUMO

BACKGROUND/AIMS: Different components of the tumor microenvironment can be either tumor-promoting or tumor-suppressive agents depending on factors which are not fully understood. Fibulins are components of the extracellular matrix from different tissues and constitute a clear example of this dual function. In fact, fibulins may either support tumor growth or abolish progression of malignant cells depending on the crosstalk between tumor cells and their surrounding stroma through mechanisms that remain to be elucidated. Among all fibulins, fibulin-5 contains a particular structural hallmark which consists in the presence of a RGD motif within its architecture. Previous reports have highlighted the importance of the interaction of this motif with integrins, and not only in normal functions but also in a tumor context. METHODS: Site-Directed Mutagenesis technique was employed to introduce the change RGD to RGE (RGD-to-RGE) within Fbln5 cDNA sequence. Cell proliferation was measured using the MTT assay or by counting Ki-67 positive cell nuclei. Cell adhesion was analysed using culture plates coated with different extracellular matrix components. Cell invasion was evaluated using 24-well Matrigel-coated invasion chambers, and mammosphere formation was monitored using ultralow attachment culture plates. BALB/c mice were employed to induce subcutaneous tumors. RESULTS: The RGD-to-RGE change alters the capacity of breast cancer cells to adhere to different extracellular matrix proteins as well as to αvß3 and α5ß1 integrins, and promotes protumor effects using different cell-based assays. Moreover, 4T1 cells, a mouse breast cancer cell line model, shows an increased capacity to generate tumors when exogenously expresses fibulin-5 with a RGD-to-RGE change, and such capacity is similar to that shown for 4T1 cells with an interfered Fbln5 gene. CONCLUSION: These data highlight the importance of the RGD motif of fibulin-5 to induce antitumor effects and provide new insights into the involvement of fibulins in tumor processes.


Assuntos
Adesão Celular/efeitos dos fármacos , Proteínas da Matriz Extracelular/farmacologia , Oligopeptídeos/metabolismo , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Caderinas/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células/efeitos dos fármacos , Proteínas da Matriz Extracelular/metabolismo , Proteínas da Matriz Extracelular/uso terapêutico , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Mutagênese Sítio-Dirigida , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Oligopeptídeos/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/farmacologia , Proteínas Recombinantes/uso terapêutico , Transplante Homólogo , Vimentina/metabolismo
6.
Dokl Biochem Biophys ; 485(1): 101-103, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31201624

RESUMO

In this paper, we present an approach to optimize the heterologous expression of the receptor tyrosine kinase IRR, which further simplifies the purification of the IRR from the medium and increases the final yield. The approach proposed by us can find application in the biotechnological production of other large-scale recombinant proteins produced for medical purposes.


Assuntos
Receptor de Insulina/biossíntese , Animais , Células CHO , Cricetinae , Cricetulus , Humanos , Domínios Proteicos , Receptor de Insulina/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética
7.
Biochemistry (Mosc) ; 84(6): 627-636, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31238862

RESUMO

The cytokine TRAIL induces apoptosis in tumor cells of various origin without affecting normal cells. Clinical trials of TRAIL-receptor (DR4 and DR5) agonists (recombinant TRAIL or death receptors antibodies) have largely failed because most human tumors were resistant to them. Currently, a second generation of agents targeted at TRAIL-R with increased efficiency has been developed. To this end, we have developed DR5-B, a variant of TRAIL selectively interacting with DR5. We have developed a new efficient method for production of TRAIL and DR5-B using expression of these proteins in Escherichia coli strain SHuffle B. The proteins were isolated from the cytoplasmic fraction of cells and purified to a high degree of homogeneity using metal-affinity and ion-exchange chromatography. The protein yield was 211 and 173 mg from one liter of cell culture for DR5-B and TRAIL, respectively, which significantly exceeded the results obtained by other methods. DR5-B killed tumor cells of different origin more efficiently and rapidly compared with TRAIL. The resulting preparations can be used for the study of TRAIL signaling pathways and in preclinical and clinical trials as antitumor agents.


Assuntos
Receptores do Ligante Indutor de Apoptose Relacionado a TNF/biossíntese , Ligante Indutor de Apoptose Relacionado a TNF/biossíntese , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Cromatografia de Afinidade/métodos , Cromatografia por Troca Iônica/métodos , Ensaios de Seleção de Medicamentos Antitumorais , Eletroforese em Gel de Poliacrilamida , Escherichia coli/genética , Humanos , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/genética , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/isolamento & purificação , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/farmacologia , Ligante Indutor de Apoptose Relacionado a TNF/genética , Ligante Indutor de Apoptose Relacionado a TNF/isolamento & purificação , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia
8.
Vet Immunol Immunopathol ; 212: 9-14, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31213252

RESUMO

Targeting antigens to endocytic receptors on the surface of dendritic cells is a new strategy for increasing the adaptive immune response. The objective of the current study was the construction and bacterial expression of a recombinant antibody single-chain fragment variable (ScFv) directed against chicken DEC 205, an endocytic receptor, for use in the genetic fusion of antigens. In particular, we use as antigen the hemagglutinin-neuraminidase (HN) of Newcastle disease virus. Our results show that inoculation of chickens with HN genetically fused to the ScFv anti-DEC 205 induced an evidently higher immune response against HN, in contrast to inoculation with unconjugated HN. In addition, neutralizing antibodies against Newcastle disease virus were detected only in the serum from chickens immunized with HN fused to ScFv anti-DEC 205. Inoculated fused antigens to ScFv against endocytic receptor DEC 205 resulted in a greater antibody-specific anti-HN production compared with antigens applied alone. The results of this study show that the strategy described here has the potential to be used in the development of more effective vaccines against infectious diseases in chickens.


Assuntos
Antígenos CD/imunologia , Lectinas Tipo C/imunologia , Antígenos de Histocompatibilidade Menor/imunologia , Vírus da Doença de Newcastle/enzimologia , Doenças das Aves Domésticas/prevenção & controle , Receptores de Superfície Celular/imunologia , Anticorpos de Cadeia Única/biossíntese , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Galinhas/imunologia , Escherichia coli/genética , Hemaglutininas Virais/imunologia , Neuraminidase/imunologia , Doenças das Aves Domésticas/imunologia , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/imunologia , Anticorpos de Cadeia Única/imunologia , Vacinas Virais/imunologia
9.
Food Chem ; 295: 653-661, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31174809

RESUMO

Although ß-xylosidases have a wide range of applications, cold-active ß-xylosidases have been poorly studied. In this study, a cold active ß-xylosidase gene (xyl) from Bacillus pumilus TCCC 11,350 was cloned and overexpressed in Escherichia coli. The recombinant XYL (rXYL) was revealed to be a bifunctional enzyme with both ß-xylosidase and α-l-arabinofuranosidase activities. Purified rXYL was most active at 30 °C, demonstrating 26% and 18% of its maximum activity at 4 °C and 0 °C, respectively. Meanwhile, rXYL showed a 52% activity in 200 mM xylose, indicating a relatively strong tolerance to xylose. Moreover, rXYL exhibited a high synergistic effect (11.14-fold and 16.21-fold) with endo-xylanase to degrade beechwood xylan in both sequential and simultaneous reactions at low temperatures. As the first report on the novel cold-adapted ß-xylosidase from B. pumilus, these results suggested rXYL had attractive properties for food industrial utilizations.


Assuntos
Bacillus pumilus/enzimologia , Xilosidases/metabolismo , Sequência de Aminoácidos , Ensaios Enzimáticos , Estabilidade Enzimática , Escherichia coli/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Filogenia , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Alinhamento de Sequência , Temperatura Ambiente , Xilanos/metabolismo , Xilose/metabolismo , Xilosidases/classificação , Xilosidases/genética
10.
Chem Biol Interact ; 309: 108698, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31176713

RESUMO

Structure-guided design of novel pharmacologically active molecules relies at least in part on functionally relevant accuracy of macromolecular structures for template based drug design. Currently, about 95% of all macromolecular X-ray structures available in the PDB (Protein Data Bank) were obtained from diffraction experiments at low, cryogenic temperatures. However, it is known that functionally relevant conformations of both macromolecules and pharmacological ligands can differ at higher, physiological temperatures. We describe in this article development and properties of new human acetylcholinesterase (AChE) crystals of space group P31 and a new unit cell, amenable for room-temperature X-ray diffraction studies. We co-crystallized hAChE in P31 unit cell with the reversible inhibitor 9-aminoacridine that binds at the base of the active center gorge in addition to inhibitors that span the full length of the gorge, donepezil (Aricept, E2020) and AChE specific inhibitor BW284c51. Their new low temperature P31 space group structures appear similar to those previously obtained in the different P3121 unit cell. Successful solution of the new room temperature 3.2 Å resolution structure of BW284c51*hAChE complex from large P31 crystals enables us to proceed with studying room temperature structures of lower affinity complexes, such as oxime reactivators bound to hAChE, where temperature-related conformational diversity could be expected in both oxime and hAChE, which could lead to better informed structure-based design under conditions approaching physiological temperature.


Assuntos
Acetilcolinesterase/química , Cristalografia por Raios X , Acetilcolinesterase/genética , Acetilcolinesterase/metabolismo , Aminacrina/química , Aminacrina/metabolismo , Sítios de Ligação , Inibidores da Colinesterase/química , Inibidores da Colinesterase/metabolismo , Dimerização , Humanos , Simulação de Dinâmica Molecular , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Temperatura Ambiente
11.
Chem Biol Interact ; 309: 108712, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31201777

RESUMO

The recent intentional use of nerve agents and pesticides in Europe and Afghanistan highlights the need for an effective countermeasure against organophosphates (OP) toxins. The most developed pretreatment candidate to date is plasma (native) human butyrylcholinesterase (HuBChE), which is limited in availability and because of its 1:1 stoichiometry with OPs, a large dose will present challenges when delivered parenterally both in terms of pharmacokinetics and manageability in the field. A tetrameric recombinant (r) form of human BChE produced in CHO-K1 cells with similar structure, in vivo stability and antidotal efficacy as the native form, has been developed to deliver rHuBChE as an aerosol (aer) to form a pulmonary bioshield capable of neutralizing inhaled OPs in situ and prevent AChE inhibition in the blood and in the brain; the latter associated with the symptoms of OP toxicity. Previous proof-of-concept macaque studies demonstrated that delivery of 9 mg/kg using a microsprayer inserted down the trachea, resulted in protection against an inhaled dose of 15ug/kg of aer-paraoxon (aer-Px) given 72 h later. In the present studies, pulmonary delivery of rHuBChE in macaques was achieved using Aerogen vibrating mesh nebulizers, similar to that used for human self-administration. The promising findings indicate that despite the poor lung deposition observed in macaques using nebulizers (13-20%), protective levels of RBC-AChE were still present in the blood even when exposure aer-Px (55 µg/kg) was delayed for five days. This long term retention of 5 mg/kg rHuBChE deposited in the lung bodes well for the use of an aer-rHuBChE pretreatment in humans where a user-friendly customized nebulizer with increased lung deposition up to 50% will provide even longer protection at a lower dose.


Assuntos
Aerossóis/química , Butirilcolinesterase/química , Paraoxon/química , Animais , Butirilcolinesterase/genética , Butirilcolinesterase/metabolismo , Células CHO , Cricetinae , Cricetulus , Feminino , Humanos , Pulmão/metabolismo , Macaca , Masculino , Nebulizadores e Vaporizadores , Paraoxon/toxicidade , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/sangue , Proteínas Recombinantes/química
12.
Chem Biol Interact ; 307: 179-185, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31063765

RESUMO

The effect of polyphenols, recognized as the principal antioxidant and beneficial molecules introduced with the diet, extracted from sweet cherry (Prunus avium L.) on the recombinant human mitochondrial carnitine/acylcarnitine transporter (CACT) has been studied in proteoliposomes. CACT transport activity, which was strongly impaired after oxidation by atmospheric O2 or H2O2, due to the formation of a disulfide bridge between cysteines 136 and 155, was restored by externally added polyphenols. CACT reduction by polyphenols was time dependent. Spectroscopic analysis of polyphenolic extracts revealed eight most represented compounds in four cultivars. Molecular docking of CACT structural omology model with the most either abundant and arguably bio-available phenolic compound (trans 3-O-feruloyl-quinic acid) of the mix, is in agreement with the experimental data since it results located in the active site close to cysteine 136 at the bottom of the translocation aqueous cavity.


Assuntos
Carnitina Aciltransferases/metabolismo , Mitocôndrias/metabolismo , Polifenóis/metabolismo , Prunus avium/química , Sítios de Ligação , Carnitina Aciltransferases/química , Carnitina Aciltransferases/genética , Humanos , Peróxido de Hidrogênio/química , Simulação de Acoplamento Molecular , Mutagênese Sítio-Dirigida , Oxirredução , Polifenóis/análise , Estrutura Terciária de Proteína , Prunus avium/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Espectrometria de Massas por Ionização por Electrospray
13.
Mol Med Rep ; 19(6): 5368-5376, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31059050

RESUMO

Cancer chemotherapy possesses high toxicity, particularly when a higher concentration of drugs is administered to patients. Therefore, searching for more effective compounds to reduce the toxicity of treatments, while still producing similar effects as current chemotherapy regimens, is required. Currently, the search for potential anticancer agents involves a random, inaccurate process with strategic deficits and a lack of specific targets. For this reason, the initial in vitro high­throughput steps in the screening process should be reviewed for rapid identification of the compounds that may serve as anticancer agents. The present study aimed to investigate the potential use of the Pichia pastoris strain SMD1168H expressing DNA topoisomerase I (SMD1168H­TOPOI) in a yeast­based assay for screening potential anticancer agents. The cell density that indicated the growth of the recombinant yeast without treatment was first measured by spectrophotometry. Subsequently, the effects of glutamate (agonist) and camptothecin (antagonist) on the recombinant yeast cell density were investigated using the same approach, and finally, the effect of camptothecin on various cell lines was determined and compared with its effect on recombinant yeast. The current study demonstrated that growth was enhanced in SMD1168H­TOPOI as compared with that in SMD1168H. Glutamate also enhanced the growth of the SMD1168H; however, the growth effect was not enhanced in SMD1168H­TOPOI treated with glutamate. By contrast, camptothecin caused only lower cell density and growth throughout the treatment of SMD1168H­TOPOI. The findings of the current study indicated that SMD1168H­TOPOI has similar characteristics to MDA­MB­231 cells; therefore, it can be used in a yeast­based assay to screen for more effective compounds that may inhibit the growth of highly metastatic breast cancer cells.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , DNA Topoisomerases Tipo I/metabolismo , Pichia/efeitos dos fármacos , Camptotecina/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , DNA Topoisomerases Tipo I/genética , Ácido Glutâmico/farmacologia , Humanos , Pichia/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética
14.
Photochem Photobiol Sci ; 18(7): 1793-1805, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31116222

RESUMO

Light-Oxygen-Voltage (LOV) domains are conserved parts of photoreceptors in plants, bacteria and fungi that bind flavins as chromophores and detect blue light. In the past, LOV domain variants have been developed as fluorescent reporter proteins (called flavin-based fluorescent proteins; FbFPs), which due to their ability to fluoresce under anaerobic conditions, fast folding kinetics and a small size of ∼12-16 kDa are a promising reporter system for quantitative real-time analysis of biological processes. Here, we present a small thermostable flavin-based fluorescent protein CagFbFP derived from a soluble LOV domain-containing histidine kinase from the thermophilic bacterium Chloroflexus aggregans. CagFbFP is composed of 107 amino acids with a molecular weight of 11.6 kDa and consists only of the conserved LOV core domain. The protein is thermostable with a melting point of about 68 °C. It crystallizes easily and its crystals diffract to 1.07 Å. Both the crystal structure and small angle scattering data show that the protein is a dimer. Unexpectedly, glutamine 148, which in LOV photoreceptor proteins is the key residue responsible for signal transduction, occupies two conformations. Molecular dynamics simulations show that the two conformations interconvert rapidly. The crystal structure of the wild-type Chloroflexus aggregans LOV domain determined at 1.22 Å resolution confirmed the presence of two alternative conformations of the glutamine 148 side chain. Overall, this protein, due to its stability and ease of crystallization, appears to be a promising model for ultra-high resolution structural studies of LOV domains and for application as a fluorescent reporter.


Assuntos
Proteínas de Bactérias/química , Chloroflexus/metabolismo , Flavinas/química , Proteínas Luminescentes/química , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cristalografia por Raios X , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Peso Molecular , Estrutura Terciária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Espalhamento a Baixo Ângulo , Alinhamento de Sequência , Espectrometria de Fluorescência , Temperatura de Transição , Difração de Raios X
15.
Food Chem ; 294: 293-301, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31126466

RESUMO

To construct a high-performance engineered endo-inulinase for fructo-oligosaccharides (FOS) production from inulin, an inulin binding module (IBM) was fused into either N- or C-terminal of an endo-inulinase. After heterologous expression, purification and characterization, the C-terminal fusion one (Eninu-IBM) with better activity, thermostability and inulin binding ability was employed for high-temperature in situ inulin hydrolysis in a 10-L fermentor. During this process, Eninu-IBM was first efficiently produced by the yeast cells at 28 °C for 96 h, and subsequently 1600 g unsterilized inulin per liter fermentation liquor was directly supplemented into the bioreactor for FOS production at 60 °C for 2 h. Finally, high purity of FOS (91.4%) were obtained with FOS titer, yield and productivity of 717.3 g/L, 0.912 gFOS/gInulin and 358.6 g/L/h, respectively. The in vitro prebiotic assay indicated that the final FOS products with main polymerization degrees of 3-5 were preferably fermented by beneficial bifidobacteria and lactobacilli.


Assuntos
Glicosídeo Hidrolases/metabolismo , Inulina/metabolismo , Oligossacarídeos/metabolismo , Reatores Biológicos , Glicosídeo Hidrolases/genética , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Prebióticos , Estabilidade Proteica , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/metabolismo , Temperatura Ambiente
16.
Microb Cell Fact ; 18(1): 80, 2019 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-31064376

RESUMO

BACKGROUND: Bacteria are widely used as hosts for recombinant protein production due to their rapid growth, simple media requirement and ability to produce high yields of correctly folded proteins. Overproduction of recombinant proteins may impose metabolic burden to host cells, triggering various stress responses, and the ability of the cells to cope with such stresses is an important factor affecting both cell growth and product yield. RESULTS: Here, we present a versatile plasmid-based reporter system for efficient analysis of metabolic responses associated with availability of cellular resources utilized for recombinant protein production and host capacity to synthesize correctly folded proteins. The reporter plasmid is based on the broad-host range RK2 minimal replicon and harbors the strong and inducible XylS/Pm regulator/promoter system, the ppGpp-regulated ribosomal protein promoter PrpsJ, and the σ32-dependent synthetic tandem promoter Pibpfxs, each controlling expression of one distinguishable fluorescent protein. We characterized the responsiveness of all three reporters in Escherichia coli by quantitative fluorescence measurements in cell cultures cultivated under different growth and stress conditions. We also validated the broad-host range application potential of the reporter plasmid by using Pseudomonas putida and Azotobacter vinelandii as hosts. CONCLUSIONS: The plasmid-based reporter system can be used for analysis of the total inducible recombinant protein production, the translational capacity measured as transcription level of ribosomal protein genes and the heat shock-like response revealing aberrant protein folding in all studied Gram-negative bacterial strains.


Assuntos
Proteínas de Escherichia coli/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Genes Reporter/genética , Plasmídeos/genética , Proteínas Recombinantes/biossíntese , Clonagem Molecular
17.
Chemistry ; 25(43): 10197-10203, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31106456

RESUMO

A simple and efficient strategy for the selective modification of the peptide N terminus with an unnatural amino acid is described. A peptide having a SUMO-HisTag-TEV sequence (SUMO: small ubiquitin-related modifier, TEV: tobacco etch virus) preceding the N terminus of the target peptide was designed. Recombinant expression in E. coli and subsequent SUMO protease cleavage yielded the HisTag-TEV-target peptide. Partial protection of the lysine side chains of this peptide with d-glucopyranosyloxycarbonyl and removal of the HisTag-TEV sequence by TEV protease yielded the partially protected peptide with a free N-terminal amine. Coupling of selenocysteine selectively at the N terminus and subsequent acidic deprotection of the carbohydrate protecting groups yielded a modified peptide that can be used for native chemical ligation (NCL). As a proof of concept, the modification of a longer recombinant peptide with selenocysteinylserine (GalNAc) at the N terminus was demonstrated.


Assuntos
Peptídeos/química , Acetilação , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão , Endopeptidases/química , Escherichia coli/metabolismo , Histidina/química , Interações Hidrofóbicas e Hidrofílicas , Oligopeptídeos/química , Peptídeos/genética , Peptídeos/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Proteína SUMO-1/química , Selenocisteína/química , Espectrometria de Massas por Ionização por Electrospray
18.
Chem Biol Interact ; 308: 235-243, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31145889

RESUMO

mHA11, a 2-amino-4-phenyl-4H-chromene-3-carboxylate analog, is a microtubule-targeting agent discovered by our group through the modification of the Bcl-2 inhibitor HA14-1. mHA11 exhibits cytotoxicities against tumor cells with nM IC50 values, whereas it has only a minimal effect on normal cells. We explored the plasma pharmacokinetics, tissue distribution, and excretion of mHA11 in rats using a liquid chromatography/tandem mass spectrometry (LC-MS/MS) method. Next, we identified the metabolites of mHA11 and assessed the influence of cytochrome P450 (CYP) isozymes on mHA11 metabolism. We also examined the in vitro stability in rat plasma and rat liver microsomes (RLMs), the blood-to plasma (B/P) ratio, and the inhibitory effect on CYP isozyme activities. After oral administration at 5, 15, and 45 mg/kg, mHA11 was absorbed and eliminated rapidly. There was a linear correlation between the area under the concentration-time curve (AUC0-∞) and the dose (R2 = 0.983). The bioavailability of mHA11 was 4.1% at the oral dose of 15 mg/kg mHA11 was extensively distributed in various tissues and exhibited a high penetration into the brain. No significant parent drug was detected in urine or bile, and only 0.74% was recovered in feces, whereas two demethylated metabolites, M1 and M2, were found in the urine and feces, and further studies showed that CYP2C19 primarily contributed to metabolites formation. mHA11 was stable in rat plasma but degraded significantly in RLMs; its B/P ratio was 1.05 in rat blood. In addition, mHA11 dose-dependently inhibited the activities of rat CYP isozymes, including CYP1A2, CYP2C6, CYP2C11, CYP2D2, CYP2E1 and CYP3A2. The present study is the first report on the disposition of mHA11 in rats and provides important data for further research and development of this inhibitor.


Assuntos
Benzopiranos/farmacocinética , Moduladores de Tubulina/farmacocinética , Administração Oral , Animais , Benzopiranos/sangue , Benzopiranos/química , Cromatografia Líquida de Alta Pressão , Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Estabilidade de Medicamentos , Humanos , Masculino , Microssomos Hepáticos/metabolismo , Ratos , Ratos Sprague-Dawley , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Espectrometria de Massas em Tandem , Distribuição Tecidual , Moduladores de Tubulina/sangue , Moduladores de Tubulina/química
19.
Ticks Tick Borne Dis ; 10(4): 935-941, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31072731

RESUMO

Tick-borne encephalitis virus (TBEV) is a member of the Flavivirus genus and is the main pathogenic arbovirus circulating in Europe, Russia and China. The envelope (E) protein is exposed on the viral surface and is the main antigen that is employed in diagnostic tests based on the detection of protein-specific antibodies from serum samples of infected individuals. The high degree of similarity among the E proteins of flaviviruses can, in some cases, lead to cross-reactivity and false-positive results in serological tests. Increased specificity in the detection of positive sera for different Flavivirus infections is often obtained by using a portion of the E protein, namely, the DIII domain. Different strategies and expression systems have been described for E and DIII protein production. Here, we present the optimization of an easy and fast method for TBEV E and DIII antigen production and partial purification from E. coli inclusion bodies. The antigenic properties of the produced antigens are retained, as validated by ELISAs with anti-TBEV murine sera as well as sera from infected human patients. The potential applications of both proteins as diagnostic reagents were confirmed.


Assuntos
Antígenos Virais/imunologia , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Escherichia coli/genética , Proteínas Recombinantes/biossíntese , Proteínas do Envelope Viral/imunologia , Animais , Anticorpos Antivirais/sangue , Antígenos Virais/biossíntese , Antígenos Virais/genética , Clonagem Molecular , Encefalite Transmitida por Carrapatos/diagnóstico , Encefalite Transmitida por Carrapatos/imunologia , Ensaio de Imunoadsorção Enzimática , Infecções por Flavivirus/diagnóstico , Infecções por Flavivirus/imunologia , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas do Envelope Viral/biossíntese , Proteínas do Envelope Viral/genética
20.
Chem Biol Interact ; 308: 101-109, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31100281

RESUMO

Eight derivatives of 4-aminoquinolines differing in the substituents attached to the C(4)-amino group and C(7) were synthesised and tested as inhibitors of human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Both enzymes were inhibited by all of the compounds with inhibition constants (Ki) ranging from 0.50 to 50 µM exhibiting slight selectivity toward AChE over BChE. The most potent inhibitors of AChE were compounds with an n-octylamino chain or adamantyl group. The shortening of the chain length resulted in a decrease in AChE inhibition by 5-20 times. Docking studies revealed that the quinoline group within the AChE active site was positioned in the choline binding site, while the C(4)-amino group substituents, depending on their lipophilicity, could establish hydrogen bonds or π-interactions with residues of the peripheral anionic site. The most potent inhibitors of BChE were compounds with the most voluminous substituent on C(4)-amino group (adamantyl) or those with a stronger electron withdrawing substituent on C(7) (trifluormethyl group). Based on AChE inhibition, compounds with an n-octylamino chain or adamantyl substituent were shown to possess the capacity for further development as potential drugs for treatment of neurodegenerative diseases.


Assuntos
Acetilcolinesterase/química , Aminoquinolinas/química , Butirilcolinesterase/química , Inibidores da Colinesterase/química , Acetilcolinesterase/genética , Acetilcolinesterase/metabolismo , Aminoquinolinas/metabolismo , Sítios de Ligação , Barreira Hematoencefálica/metabolismo , Butirilcolinesterase/genética , Butirilcolinesterase/metabolismo , Domínio Catalítico , Inibidores da Colinesterase/metabolismo , Humanos , Cinética , Simulação de Acoplamento Molecular , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação
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