RESUMO
The ClC-3 chloride/proton exchanger is both physiologically and pathologically critical, as it is potentiated by ATP to detect metabolic energy level and point mutations in ClC-3 lead to severe neurodegenerative diseases in human. However, why this exchanger is differentially modulated by ATP, ADP or AMP and how mutations caused gain-of-function remains largely unknow. Here we determine the high-resolution structures of dimeric wildtype ClC-3 in the apo state and in complex with ATP, ADP and AMP, and the disease-causing I607T mutant in the apo and ATP-bounded state by cryo-electron microscopy. In combination with patch-clamp recordings and molecular dynamic simulations, we reveal how the adenine nucleotides binds to ClC-3 and changes in ion occupancy between apo and ATP-bounded state. We further observe I607T mutation induced conformational changes and augments in current. Therefore, our study not only lays the structural basis of adenine nucleotides regulation in ClC-3, but also clearly indicates the target region for drug discovery against ClC-3 mediated neurodegenerative diseases.
Assuntos
Trifosfato de Adenosina , Canais de Cloreto , Microscopia Crioeletrônica , Simulação de Dinâmica Molecular , Doenças Neurodegenerativas , Canais de Cloreto/metabolismo , Canais de Cloreto/genética , Canais de Cloreto/química , Humanos , Trifosfato de Adenosina/metabolismo , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/patologia , Nucleotídeos de Adenina/metabolismo , Técnicas de Patch-Clamp , Mutação , Difosfato de Adenosina/metabolismo , Células HEK293 , Monofosfato de Adenosina/metabolismo , Animais , Conformação ProteicaRESUMO
In the type III CRISPR system, cyclic oligoadenylate (cOA) molecules act as second messengers, activating various promiscuous ancillary nucleases that indiscriminately degrade host and viral DNA/RNA. Conversely, ring nucleases, by specifically cleaving cOA molecules, function as off-switches to protect host cells from dormancy or death, and allow viruses to counteract immune responses. The fusion protein Csx1-Crn2, combining host ribonuclease with viral ring nuclease, represents a unique self-limiting ribonuclease family. Here, we describe the structures of Csx1-Crn2 from the organism of Marinitoga sp., in both its full-length and truncated forms, as well as in complex with cA4. We show that Csx1-Crn2 operates as a homo-tetramer, a configuration crucial for preserving the structural integrity of the HEPN domain and ensuring effective ssRNA cleavage. The binding of cA4 to the CARF domain triggers significant conformational changes across the CARF, HTH, and into the HEPN domains, leading the two R-X4-6-H motifs to form a composite catalytic site. Intriguingly, an acetate ion was found to bind at this composite site by mimicking the scissile phosphate. Further molecular docking analysis reveals that the HEPN domain can accommodate a single ssRNA molecule involving both R-X4-6-H motifs, underscoring the importance of HEPN domain dimerization for its activation.
Assuntos
Proteínas de Bactérias , Proteínas Associadas a CRISPR , Sistemas CRISPR-Cas , Nucleotídeos de Adenina/metabolismo , Nucleotídeos de Adenina/química , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas Associadas a CRISPR/metabolismo , Proteínas Associadas a CRISPR/química , Proteínas Associadas a CRISPR/genética , Modelos Moleculares , Oligorribonucleotídeos , Ligação Proteica , Domínios Proteicos , Multimerização Proteica , Ribonucleases/metabolismo , Ribonucleases/química , Ribonucleases/genéticaRESUMO
BACKGROUND/AIM: ClFdA is a second-generation antineoplastic agent that has demonstrated significant anticancer activity, particularly against acute lymphoblastic leukemia and has been shown to have radiosensitizing activity. The aim of the study was to explore the genotoxic, cytotoxic and radiosensitizing effects of clofarabine (ClFdA) on bone marrow cells (BMCs), normoblasts and leukocytes of mice in vivo. MATERIALS AND METHODS: Cytotoxicity was determined by the reduction in reticulocytes (RET), and genotoxicity was determined by the induction of micronucleated reticulocytes (MN-RET) in the peripheral blood and by DNA break induction in leukocytes determined by single-cell gel electrophoresis (SCGE). The radiosensitizing capacity of ClFdA was determined in leukocytes and BMCs by SCGE. RESULTS: Two mechanisms of MN-RET induction were identified according to the antecedents, that could be due to inhibition of DNA synthesis and demethylation of G-C regions, and subsequent chromosome fragility. ClFdA cytotoxicity causes two contiguous peaks, an early peak that seems to inhibit MN-RET induction and a second peak that seems to be caused by ribonucleotide reductase (RR) and/or DNA synthesis inhibitions. ClFdA induced early DNA damage in noncycling leukocytes, and also radiosensitizes leukocytes immediately after treatment. ClFdA-ionizing radiation (IR) causes two time-dependent episodes of DNA damage, the latest after 80 min triggers a major breakage of DNA. In terms of the number of damaged cells, leukocytes and BMCs are similarly sensitive to ionizing radiation; BMCs are slightly more sensitive than leukocytes to ClFdA, but BMCs are doubly sensitive to combined treatment. CONCLUSION: ClFdA causes early DNA damage and radiosensitivity in non-proliferating leukocytes, which rules out the most favored hypotheses of the participation of RR and DNA polymerase inhibition.
Assuntos
Clofarabina , Dano ao DNA , Leucócitos , Radiossensibilizantes , Animais , Clofarabina/farmacologia , Camundongos , Radiossensibilizantes/farmacologia , Leucócitos/efeitos dos fármacos , Leucócitos/efeitos da radiação , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , Arabinonucleosídeos/farmacologia , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/efeitos da radiação , Células da Medula Óssea/metabolismo , Nucleotídeos de Adenina/farmacologia , Masculino , Reticulócitos/efeitos dos fármacos , Reticulócitos/efeitos da radiação , Antineoplásicos/farmacologia , Testes para MicronúcleosRESUMO
Regulatory cystathionine ß-synthase (CBS) domains are widespread in proteins; however, difficulty in structure determination prevents a comprehensive understanding of the underlying regulation mechanism. Tetrameric microbial inorganic pyrophosphatase containing such domains (CBS-PPase) is allosterically inhibited by AMP and ADP and activated by ATP and cell alarmones diadenosine polyphosphates. Each CBS-PPase subunit contains a pair of CBS domains but binds cooperatively to only one molecule of the mono-adenosine derivatives. We used site-directed mutagenesis of Desulfitobacterium hafniense CBS-PPase to identify the key elements determining the direction of the effect (activation or inhibition) and the "half-of-the-sites" ligand binding stoichiometry. Seven amino acid residues were selected in the CBS1 domain, based on the available X-ray structure of the regulatory domains, and substituted by alanine and other residues. The interaction of 11 CBS-PPase variants with the regulating ligands was characterized by activity measurements and isothermal titration calorimetry. Lys100 replacement reversed the effect of ADP from inhibition to activation, whereas Lys95 and Gly118 replacements made ADP an activator at low concentrations but an inhibitor at high concentrations. Replacement of these residues for alanine increased the stoichiometry of mono-adenosine phosphate binding by twofold. These findings identified several key protein residues and suggested a "two non-interacting pairs of interacting regulatory sites" concept in CBS-PPase regulation.
Assuntos
Cistationina beta-Sintase , Cistationina beta-Sintase/metabolismo , Cistationina beta-Sintase/química , Cistationina beta-Sintase/genética , Mutação , Ligação Proteica , Mutagênese Sítio-Dirigida , Nucleotídeos de Adenina/metabolismo , Nucleotídeos de Adenina/química , Domínios Proteicos , Pirofosfatases/metabolismo , Pirofosfatases/química , Pirofosfatases/genética , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Pirofosfatase Inorgânica/metabolismo , Pirofosfatase Inorgânica/química , Pirofosfatase Inorgânica/genética , Modelos Moleculares , Sítios de LigaçãoRESUMO
Favipiravir (FVP) is an oral antiviral drug approved in 2021 for the treatment of COVID-19. It is a pyrazine derivative that can be integrated into anti-viral RNA products to inhibit viral replication. While, adenine is a purine nucleobase that is found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to generate genetic information. For the first time, the binding mechanism between FVP and adenine was determined using different techniques, including UV-visible spectrophotometry, spectrofluorimetry, synchronous fluorescence (SF) spectroscopy, Fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET), and metal ion complexation. The fluorescence spectra indicated that FVP is bound to adenine via Van der Waals forces and hydrogen bonding through a spontaneous binding process (ΔGο < 0). The quenching mechanism was found to be static. Various temperature settings were used to investigate thermodynamic characteristics, such as binding forces, binding constants, and the number of binding sites. The reaction parameters, including the enthalpy change (ΔHο) and entropy change (ΔSο), were calculated using Van't Hoff's equation. The findings demonstrated that the adenine-FVP binding was endothermic. Furthermore, the results of the experiments revealed that some metal ions (K+, Ca+2, Co+2, Cu+2, and Al+3) might facilitate the binding interaction between FVP and adenine. Slight changes are observed in the FTIR spectra of adenine, indicating the binding interaction between adenine and FVP. This study may be useful in understanding the pharmacokinetic characteristics of FVP and how the drug binds to adenine to prevent any side effects.
Assuntos
Nucleotídeos de Adenina , Amidas , Antivirais , Pirazinas , Termodinâmica , Pirazinas/química , Pirazinas/metabolismo , Amidas/química , Amidas/metabolismo , Nucleotídeos de Adenina/química , Nucleotídeos de Adenina/metabolismo , Antivirais/química , Antivirais/farmacologia , Antivirais/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Espectrometria de Fluorescência , Transferência Ressonante de Energia de Fluorescência , Espectrofotometria Ultravioleta , Sítios de Ligação , Adenina/química , Adenina/metabolismoRESUMO
BACKGROUND: Lipid metabolism changes occur in early Alzheimer's disease (AD) patients. Yet little is known about metabolic gene changes in early AD cortex. METHODS: The lipid metabolic genes selected from two datasets (GSE39420 and GSE118553) were analyzed with enrichment analysis. Protein-protein interaction network construction and correlation analyses were used to screen core genes. Literature analysis and molecular docking were applied to explore potential therapeutic drugs. RESULTS: 60 lipid metabolic genes differentially expressed in early AD patients' cortex were screened. Bioinformatics analyses revealed that up-regulated genes were mainly focused on mitochondrial fatty acid oxidation and mediating the activation of long-chain fatty acids, phosphoproteins, and cholesterol metabolism. Down-regulated genes were mainly focused on lipid transport, carboxylic acid metabolic process, and neuron apoptotic process. Literature reviews and molecular docking results indicated that ACSL1, ACSBG2, ACAA2, FABP3, ALDH5A1, and FFAR4 were core targets for lipid metabolism disorder and had a high binding affinity with compounds including adenosine phosphate, oxidized Photinus luciferin, BMS-488043, and candidate therapeutic drugs especially bisphenol A, benzo(a)pyrene, ethinyl estradiol. CONCLUSIONS: AD cortical lipid metabolism disorder was associated with the dysregulation of the PPAR signaling pathway, glycerophospholipid metabolism, adipocytokine signaling pathway, fatty acid biosynthesis, fatty acid degradation, ferroptosis, biosynthesis of unsaturated fatty acids, and fatty acid elongation. Candidate drugs including bisphenol A, benzo(a)pyrene, ethinyl estradiol, and active compounds including adenosine phosphate, oxidized Photinus luciferin, and BMS-488043 have potential therapeutic effects on cortical lipid metabolism disorder of early AD.
Assuntos
Doença de Alzheimer , Compostos Benzidrílicos , Indóis , Transtornos do Metabolismo dos Lipídeos , Fenóis , Piperazinas , Ácido Pirúvico , Humanos , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Simulação de Acoplamento Molecular , Benzo(a)pireno , Ácidos Graxos/metabolismo , Redes e Vias Metabólicas , Etinilestradiol , Nucleotídeos de Adenina/metabolismo , LuciferinasRESUMO
CRISPR-Cas provides adaptive immunity in prokaryotes. Type III CRISPR systems detect invading RNA and activate the catalytic Cas10 subunit, which generates a range of nucleotide second messengers to signal infection. These molecules bind and activate a diverse range of effector proteins that provide immunity by degrading viral components and/or by disturbing key aspects of cellular metabolism to slow down viral replication. Here, we focus on the uncharacterised effector Csx23, which is widespread in Vibrio cholerae. Csx23 provides immunity against plasmids and phage when expressed in Escherichia coli along with its cognate type III CRISPR system. The Csx23 protein localises in the membrane using an N-terminal transmembrane α-helical domain and has a cytoplasmic C-terminal domain that binds cyclic tetra-adenylate (cA4), activating its defence function. Structural studies reveal a tetrameric structure with a novel fold that binds cA4 specifically. Using pulse EPR, we demonstrate that cA4 binding to the cytoplasmic domain of Csx23 results in a major perturbation of the transmembrane domain, consistent with the opening of a pore and/or disruption of membrane integrity. This work reveals a new class of cyclic nucleotide binding protein and provides key mechanistic detail on a membrane-associated CRISPR effector.
Many anti-viral defence systems generate a cyclic nucleotide signal that activates cellular defences in response to infection. Type III CRISPR systems use a specialised polymerase to make cyclic oligoadenylate (cOA) molecules from ATP. These can bind and activate a range of effector proteins that slow down viral replication. In this study, we focussed on the Csx23 effector from the human pathogen Vibrio cholerae a trans-membrane protein that binds a cOA molecule, leading to anti-viral immunity. Structural studies revealed a new class of nucleotide recognition domain, where cOA binding is transmitted to changes in the trans-membrane domain, most likely resulting in membrane depolarisation. This study highlights the diversity of mechanisms for anti-viral defence via nucleotide signalling.
Assuntos
Proteínas de Bactérias , Proteínas Associadas a CRISPR , Vibrio cholerae , Nucleotídeos de Adenina/metabolismo , Proteínas Associadas a CRISPR/metabolismo , Sistemas CRISPR-Cas/genética , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Nucleotídeos Cíclicos , Sistemas do Segundo Mensageiro , Proteínas de Bactérias/metabolismo , Vibrio cholerae/metabolismoRESUMO
Over 50% of patients with systemic LCH are not cured with front-line therapies, and data to guide salvage options are limited. We describe 58 patients with LCH who were treated with clofarabine. Clofarabine monotherapy was active against LCH in this cohort, including heavily pretreated patients with a systemic objective response rate of 92.6%, higher in children (93.8%) than adults (83.3%). BRAFV600E+ variant allele frequency in peripheral blood is correlated with clinical responses. Prospective multicentre trials are warranted to determine optimal dosing, long-term efficacy, late toxicities, relative cost and patient-reported outcomes of clofarabine compared to alternative LCH salvage therapy strategies.
Assuntos
Clofarabina , Histiocitose de Células de Langerhans , Humanos , Clofarabina/uso terapêutico , Clofarabina/administração & dosagem , Histiocitose de Células de Langerhans/tratamento farmacológico , Masculino , Feminino , Adulto , Adolescente , Criança , Pessoa de Meia-Idade , Pré-Escolar , Adulto Jovem , Idoso , Recidiva , Proteínas Proto-Oncogênicas B-raf/genética , Lactente , Resultado do Tratamento , Terapia de Salvação , Nucleotídeos de Adenina/uso terapêutico , Nucleotídeos de Adenina/administração & dosagem , Nucleotídeos de Adenina/efeitos adversos , Arabinonucleosídeos/uso terapêutico , Arabinonucleosídeos/administração & dosagem , Arabinonucleosídeos/efeitos adversosRESUMO
RNase L is an endoribonuclease of higher vertebrates that functions in antiviral innate immunity. Interferons induce oligoadenylate synthetase enzymes that sense double-stranded RNA of viral origin leading to the synthesis of 2',5'-oligoadenylate (2-5A) activators of RNase L. However, it is unknown precisely how RNase L remodels the host cell transcriptome. To isolate effects of RNase L from other effects of double-stranded RNA or virus, 2-5A is directly introduced into cells. Here, we report that RNase L activation by 2-5A causes a ribotoxic stress response involving the MAP kinase kinase kinase (MAP3K) ZAKα, MAP2Ks, and the stress-activated protein kinases JNK and p38α. RNase L activation profoundly alters the transcriptome by widespread depletion of mRNAs associated with different cellular functions but also by JNK/p38α-stimulated induction of inflammatory genes. These results show that the 2-5A/RNase L system triggers a protein kinase cascade leading to proinflammatory signaling and apoptosis.
Assuntos
Endorribonucleases , Imunidade Inata , Endorribonucleases/metabolismo , Endorribonucleases/genética , Humanos , Nucleotídeos de Adenina/metabolismo , Oligorribonucleotídeos/metabolismo , Animais , Estresse Fisiológico , Transcriptoma/genética , RNA de Cadeia Dupla/metabolismoRESUMO
In response to viral infection, how cells balance translational shutdown to limit viral replication and the induction of antiviral components like interferons (IFNs) is not well understood. Moreover, how distinct isoforms of IFN-induced oligoadenylate synthetase 1 (OAS1) contribute to this antiviral response also requires further elucidation. Here, we show that human, but not mouse, OAS1 inhibits SARS-CoV-2 replication through its canonical enzyme activity via RNase L. In contrast, both mouse and human OAS1 protect against West Nile virus infection by a mechanism distinct from canonical RNase L activation. OAS1 binds AU-rich elements (AREs) of specific mRNAs, including IFNß. This binding leads to the sequestration of IFNß mRNA to the endomembrane regions, resulting in prolonged half-life and continued translation. Thus, OAS1 is an ARE-binding protein with two mechanisms of antiviral activity: driving inhibition of translation but also a broader, non-canonical function of protecting IFN expression from translational shutdown.
Assuntos
2',5'-Oligoadenilato Sintetase , Interferons , Oligorribonucleotídeos , Viroses , Febre do Nilo Ocidental , Animais , Humanos , Camundongos , 2',5'-Oligoadenilato Sintetase/genética , 2',5'-Oligoadenilato Sintetase/metabolismo , Nucleotídeos de Adenina , Antivirais/farmacologia , Febre do Nilo Ocidental/genética , Febre do Nilo Ocidental/metabolismo , Vírus do Nilo Ocidental/metabolismo , Vírus do Nilo Ocidental/patogenicidadeRESUMO
Pancreatic ductal adenocarcinoma (PDAC) is a highly invasive cancer with a poor prognosis and a 5-year survival rate of less than 11%. As a member of the CAP superfamily of proteins, the role of peptidase inhibitor 16 (Pi16) in tumor progression is still unclear. Immunohistochemistry and quantitative RT-PCR methods were used to detect the expression levels of Pi16 protein and mRNA in PDAC patients. CRISPR/Cas9 technology was used to knock out the expression of Pi16 in PDAC cell lines. In vivo and in vitro experiments were used to verify the effect of Pi16 on PDAC proliferation ability. By RNA sequencing, we found that oligoadenylate synthetase L (OASL) can serve as a potential downstream target of Pi16. The expression of Pi16 was higher in PDAC tissues than in matched adjacent tissues. High expression of Pi16 was associated with PDAC progression and poor prognosis. Overexpression of Pi16 could promote the proliferation of PDAC cells in vitro and in vivo. Bioinformatics analysis and coimmunoprecipitation assays showed that Pi16 could bind to OASL. Moreover, the functional recovery test confirmed that Pi16 could promote the proliferation of PDAC via OASL. Our present study demonstrates that Pi16 might participate in the occurrence and development of PDAC by regulating cell proliferation by binding to OASL, indicating that Pi16 might be a promising novel therapeutic target for PDAC.
Assuntos
2',5'-Oligoadenilato Sintetase , Nucleotídeos de Adenina , Carcinoma Ductal Pancreático , Glicoproteínas , Neoplasias Pancreáticas , Humanos , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patologia , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Glicoproteínas/metabolismo , Proteínas de Transporte/metabolismo , 2',5'-Oligoadenilato Sintetase/metabolismoRESUMO
OBJECTIVE: Several studies have shown that mitochondrial metabolism may be disrupted if the rate of the specific 4,977 bp deletion of mitochondrial DNA (mtDNA) reaches a threshold. This study aimed to investigate the possible associations between the mtDNA4977 deletion load and obesity-related metabolic abnormalities in the adipose tissue. METHODS: The study included thirty obese individuals, who underwent bariatric surgery, and twelve control subjects. mtDNA4977 deletion, adenine nucleotides, and lactate levels, which show the bioenergetic status were evaluated in visceral adipose tissues. Fourier transform infrared (FTIR) spectroscopy was used to investigate the structural variations and composition of adipose tissues in the context of deletion load. RESULTS: There were no differences between the two groups in terms of mtDNA4977 deletion, adenine nucleotides, and lactate levels. The FTIR spectra indicated a few obesity-related alterations in adipose tissues that were not related to the mtDNA deletion load. Also, statistical analysis showed a correlation between the deletion load and a band shift of 1,744 cm-1, which assigns C = O stretching of the carbonyl group of the ester group in triglycerides and other esterified fatty acids, although it is not associated with obesity. CONCLUSIONS: Our data suggest that the mtDNA4977 deletion in visceral adipose tissues of obese individuals do not have a significant impact on the bioenergetic status. However, the increased accumulation of deletion may be associated with a specific change in the ester bond, indicating structural differences in the lipids. These findings shed light on our understanding of the tissue-specific distribution of mtDNA deletions and obesity-related adipose tissue pathogeneses.
Assuntos
DNA Mitocondrial , Obesidade , Humanos , Espectroscopia de Infravermelho com Transformada de Fourier , Triglicerídeos , Obesidade/genética , DNA Mitocondrial/genética , Nucleotídeos de Adenina , Tecido Adiposo/metabolismo , Ésteres , LactatosRESUMO
Adenine nucleotides (AN) are ubiquitous metabolites that regulate cellular energy metabolism and modulate cell communication and inflammation. To understand how disturbances in AN balance arise and affect cellular function, robust quantification techniques for these metabolites are crucial. However, due to their hydrophilicity, simultaneous quantification of AN across various biological samples has been challenging. Here we present a hydrophilic interaction high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) based method for the quantification of 26 adenosine nucleotides and precursors as well as metabolic products of nicotinamide adenine dinucleotide (NAD) in plasma, liver, and adipose tissue samples as well as cell culture supernatants and cells. Method validation was performed with regard to linearity, accuracy, precision, matrix effects, and carryover. Finally, analysis of cell culture supernatants derived from intestinal organoids and RAW 264.7 cells illustrates that the here described method is a reliable and easy-to-use tool to quantify AN and opens up new avenues to understand the role of AN generation and breakdown for cellular functions.
Assuntos
NAD , Nucleotídeos , NAD/metabolismo , Nucleotídeos/metabolismo , Espectrometria de Massas em Tandem/métodos , Adenosina , Cromatografia Líquida/métodos , Nucleotídeos de AdeninaRESUMO
Polymorphic toxins (PTs) are a broad family of toxins involved in interbacterial competition and pathogenesis. PTs are modular proteins that are comprised of a conserved N-terminal domain responsible for its transport, and a variable C-terminal domain bearing toxic activity. Although the mode of transport has yet to be elucidated, a new family of putative PTs containing an N-terminal MuF domain, resembling the Mu coliphage F protein, was identified in prophage genetic elements. The C-terminal toxin domains of these MuF PTs are predicted to bear nuclease, metallopeptidase, ADP-ribosyl transferase and RelA_SpoT activities. In this study, we characterized the MuF-RelA_SpoT toxin associated with the temperate phage of Streptococcus pneumoniae SPNA45. We show that the RelA_SpoT domain has (p)ppApp synthetase activity, which is bactericidal under our experimental conditions. We further determine that the two genes located downstream encode two immunity proteins, one binding to and inactivating the toxin and the other detoxifying the cell via a pppApp hydrolase activity. Finally, based on protein sequence alignments, we propose a signature for (p)ppApp synthetases that distinguishes them from (p)ppGpp synthetases.
Assuntos
Ligases , Fagos de Streptococcus , Toxinas Biológicas , Ligases/química , Ligases/metabolismo , Alinhamento de Sequência , Toxinas Biológicas/química , Toxinas Biológicas/metabolismo , Streptococcus pneumoniae/virologia , Fagos de Streptococcus/enzimologia , Escherichia coli , Domínios Proteicos , Nucleotídeos de Adenina/biossínteseRESUMO
2'-5' Oligoadenylate synthetases (OAS) are interferon-stimulated genes that are most well-known to protect hosts from viral infections. They are evolutionarily related to an ancient family of Nucleotidyltransferases, which are primarily involved in pathogen-sensing and innate immune response. Classical function of OAS proteins involves double-stranded RNA-stimulated polymerization of adenosine triphosphate in 2'-5' oligoadenylates (2-5A), which can activate the latent RNase (RNase L) to degrade RNA. However, accumulated evidence over the years have suggested alternative mode of antiviral function of several OAS family proteins. Furthermore, recent studies have connected some OAS proteins with wider function beyond viral infection. Here, we review some of the canonical and noncanonical functions of OAS proteins and their mechanisms.
Assuntos
RNA de Cadeia Dupla , Viroses , Humanos , Interferons/genética , Nucleotídeos de Adenina , Oligorribonucleotídeos , Endorribonucleases/genética , Endorribonucleases/metabolismo , 2',5'-Oligoadenilato Sintetase/genética , 2',5'-Oligoadenilato Sintetase/metabolismoRESUMO
Physiological function analysis of terminal deoxynucleotidyl transferase (TdT) in clinical medicine and hematopathology highlights its significance to be extensively utilized as a diagnostic biomarker for leukemia diagnosis. Herein, taking advantage of the spatial-confinement effect on a three-dimensional (3D) DNA nanoarchitecture, we reported a target-triggered intramolecular accelerated molecular beacon (MB) assembly for rapid and real-time analysis of TdT activity. In this strategy, the 3D DNA nanoarchitecture is first engineered via a cross-linking network hybridization chain reaction (HCR). A number of MBs, which were designed with a polythymine (poly-T) loop, were then conjugated on the scaffold DNA nanoarchitecture, allowing the obtained MB-DNA nanoarchitecture to contain lots of free 3'-hydroxyl (OH) termini inside or outside the super DNA nanostructure. Moreover, the distance between different MBs is closed, and the local concentration of MB is significantly improved owing to the confinement of MBs on this DNA nanoarchitecture. Once encountered with target TdT, the free -OH groups can be recognized by TdT immediately to catalyze the template-independent incorporation of adenine nucleotides, which results in the generation of multiple poly-A chains that rapidly react with many MBs via an intramolecular accelerated assembly process. The time-dependent substantial enhancement of the fluorescence from MBs can thus be applied for robustly analyzing TdT. Our observations suggest that the DNA nanostructure-based spatial confinement effect enables a high molecular collision frequency to accelerate the reaction kinetics, and the super DNA nanoarchitecture exhibits a better nuclease resistance to maintain signal stability. With these advantages, TdT can be rapidly detected with high sensitivity, specificity, and biostability.
Assuntos
DNA Nucleotidilexotransferase , DNA Polimerase Dirigida por DNA , Nucleotídeos de Adenina , Catálise , CorantesRESUMO
β1,3-galactose is the component of outer-chain elongation of complex N-glycans that, together with α1,4-fucose, forms Lewis a structures in plants. Previous studies have revealed that N-glycan maturation is mediated by sequential attachment of β1,3-galactose and α1,4-fucose by individual β1,3-galactosyltransferase (GalT) and α1,4-fucosyltransferase (1,4-FucT), respectively. Although GalT from several species has been studied, little information about GalT from rice is available. I therefore characterized three GalT candidate genes on different chromosomes in Oryza sativa. Seeds of rice lines that had T-DNA insertions in regions corresponding to individual putative GalT genes were obtained from a Rice Functional Genomic Express Database and plants grown until maturity. Homozygotes were selected from the next generation by genotyping PCR, and used for callus induction. Callus extracts of two independent T-DNA mutant rice which have T-DNA insertions at the same gene on chromosome 6 but in different exons showed highly reduced band intensity on a western blots using an anti-Lewis a antibody. Cell extracts and cultured media from suspension culture of the one of these mutant rice were further analysed by N-glycan profiling using matrix-associated laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF). Identified N-glycan species containing β1,3-galactose from both cell extracts and cultured media of knock-out mutant were less than 0.5% of total N-glycans while that of WT cells were 9.8% and 49.1%, respectively. This suggests that GalT located on rice chromosome 6 plays a major role in N-glycan galactosylation, and mutations within it lead to blockage of Lewis a epitope formation.
Assuntos
Radiação não IonizanteNucleotídeos de Adenina , 5643 , Doenças dos Bovinos , Ácido FormiminoglutâmicoNucleotídeos de Adenina , 6801 , Radiação não IonizanteNucleotídeos de Adenina , Cromatografia em Agarose , Percepção de Forma , 11134Nucleotídeos de AdeninaRESUMO
BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by genetic heterogeneity and an interferon (IFN) signature. The overall landscapes of the heritability of SLE remains unclear. OBJECTIVES: To identify and elucidate the biological functions of rare variants underlying SLE, we conducted analyses of patient-derived induced pluripotent stem cells (iPSCs) in combination with genetic analysis. METHODS: Two familial SLE patient- and two healthy donor (HD)-derived iPSCs were established. Type 1 IFN-secreting dendritic cells (DCs) were differentiated from iPSCs. Genetic analyses of SLE-iPSCs, and 117 SLE patients and 107 HDs in the ImmuNexUT database were performed independently. Genome editing of the variants on iPSCs was performed with the CRISPR/Cas9 system. RESULTS: Type 1 IFN secretion was significantly increased in DCs differentiated from SLE-iPSCs compared to HD-iPSCs. Genetic analyses revealed a rare variant in the 2'-5'-Oligoadenylate Synthetase Like (OASL) shared between SLE-iPSCs and another independent SLE patient, and significant accumulation of OASL variants among SLE patients (HD 0.93%, SLE 6.84%, OR 8.387) in the database. Genome editing of mutated OASL 202Q to wild-type 202 R or wild-type OASL 202 R to mutated 202Q resulted in reduced or enhanced Type 1 IFN secretion of DCs. Three other OASL variants (R60W, T261S and A447V) accumulated in SLE patients had also capacities to enhance Type 1 IFN secretion in response to dsRNA. CONCLUSIONS: We established a patient-derived iPSC-based strategy to investigate the linkage of genotype and phenotype in autoimmune diseases. Detailed case-based investigations using patient-derived iPSCs provide information to unveil the heritability of the pathogenesis of autoimmune diseases.
Assuntos
Células-Tronco Pluripotentes Induzidas , Lúpus Eritematoso Sistêmico , Humanos , Interferons , Nucleotídeos de Adenina , Lúpus Eritematoso Sistêmico/genéticaRESUMO
An analogue of a toxic moiety (TM84) of natural product agrocin 84 containing threonine amide instead of 2,3-dihydroxy-4-methylpentanamide was prepared and evaluated as a putative Plasmodium falciparum threonyl t-RNA synthetase (PfThrRS) inhibitor. This TM84 analogue features submicromolar inhibitory potency (IC50 = 440 nM) comparable to that of borrelidin (IC50 = 43 nM) and therefore complements chemotypes known to inhibit malarial PfThrRS, which are currently limited to borrelidin and its analogues. The crystal structure of the inhibitor in complex with the E. coli homologue enzyme (EcThrRS) was obtained, revealing crucial ligand-protein interactions that will pave the way for the design of novel ThrRS inhibitors.