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1.
Nat Chem Biol ; 19(2): 218-229, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36443572

RESUMO

Bifidobacteria are early colonizers of the human gut and play central roles in human health and metabolism. To thrive in this competitive niche, these bacteria evolved the capacity to use complex carbohydrates, including mammalian N-glycans. Herein, we elucidated pivotal biochemical steps involved in high-mannose N-glycan utilization by Bifidobacterium longum. After N-glycan release by an endo-ß-N-acetylglucosaminidase, the mannosyl arms are trimmed by the cooperative action of three functionally distinct glycoside hydrolase 38 (GH38) α-mannosidases and a specific GH125 α-1,6-mannosidase. High-resolution cryo-electron microscopy structures revealed that bifidobacterial GH38 α-mannosidases form homotetramers, with the N-terminal jelly roll domain contributing to substrate selectivity. Additionally, an α-glucosidase enables the processing of monoglucosylated N-glycans. Notably, the main degradation product, mannose, is isomerized into fructose before phosphorylation, an unconventional metabolic route connecting it to the bifid shunt pathway. These findings shed light on key molecular mechanisms used by bifidobacteria to use high-mannose N-glycans, a perennial carbon and energy source in the intestinal lumen.


Assuntos
Bifidobacterium longum , Manose , Animais , Humanos , Manose/metabolismo , Bifidobacterium longum/metabolismo , Microscopia Crioeletrônica , Polissacarídeos/química , Manosidases/metabolismo , Glicosídeo Hidrolases/química , Bifidobacterium/metabolismo , Mamíferos
2.
Int J Mol Sci ; 25(10)2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38791254

RESUMO

Mycoses are one of the major causes of morbidity/mortality among immunocompromised individuals. Considering the importance of these infections, the World Health Organization (WHO) defined a priority list of fungi for health in 2022 that include Candida albicans as belonging to the critical priority group and Pichia kudriavzevii (Candida krusei) to the medium priority group. The existence of few available antifungal drugs, their high toxicity, the acquired fungal resistance, and the appearance of new species with a broader spectrum of resistance, points out the need for searching for new antifungals, preferably with new and multiple mechanisms of action. The cyclam salt H4[H2(4-CF3PhCH2)2Cyclam]Cl4 was previously tested against several fungi and revealed an interesting activity, with minimal inhibitory concentration (MIC) values of 8 µg/mL for C. krusei and of 128 µg/mL for C. albicans. The main objective of the present work was to deeply understand the mechanisms involved in its antifungal activity. The effects of the cyclam salt on yeast metabolic viability (resazurin reduction assay), yeast mitochondrial function (JC-1 probe), production of reactive oxygen species (DCFH-DA probe) and on intracellular ATP levels (luciferin/luciferase assay) were evaluated. H4[H2(4-CF3PhCH2)2Cyclam]Cl4 induced a significant decrease in the metabolic activity of both C. albicans and C. krusei, an increase in Reactive Oxygen Species (ROS) production, and an impaired mitochondrial function. The latter was observed by the depolarization of the mitochondrial membrane and decrease in ATP intracellular levels, mechanisms that seems to be involved in the antifungal activity of H4[H2(4-CF3PhCH2)2Cyclam]Cl4. The interference of the cyclam salt with human cells revealed a CC50 value against HEK-293 embryonic kidney cells of 1.1 µg/mL and a HC10 value against human red blood cells of 0.8 µg/mL.


Assuntos
Antifúngicos , Candida albicans , Candida , Testes de Sensibilidade Microbiana , Espécies Reativas de Oxigênio , Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Humanos , Espécies Reativas de Oxigênio/metabolismo , Candida/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Pichia
3.
Biochem Biophys Res Commun ; 645: 71-78, 2023 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-36680939

RESUMO

Carbohydrate-binding modules (CBMs) constitute independently folded domains typically associated with carbohydrate-active enzymes (CAZymes). These modules are considered to have a rigid structure without notable conformational changes upon ligand binding, exhibiting a complementary topography in relation to the target carbohydrate. Herein, the high-resolution SAD-solved structure of a CBM from family 3 (BsCBM3) that binds to crystalline cellulose is reported in two crystalline forms. This module showed molecular plasticity with structural differences detected between the two crystalline forms and high RMSD values when compared to NMR ensemble of models. Pronounced structural variances were observed in the cellulose binding interface between NMR and XTAL structures, which were corroborated by molecular dynamics simulations. These findings support that family 3 CBMs targeting to cellulose are rather structurally dynamic modules than rigid entities, suggesting a potential role of conformational changes in polysaccharide recognition and modulation of enzyme activity.


Assuntos
Carboidratos , Celulose , Celulose/química , Carboidratos/química , Polissacarídeos , Simulação de Dinâmica Molecular , Ligação Proteica , Cristalografia por Raios X
4.
Molecules ; 27(14)2022 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-35889459

RESUMO

Psoralen (PSO) and 5-methoxypsoralen (5-MOP) are widely used drugs in oral photochemotherapy against vitiligo and major bioactive components of root bark extract of Brosimum gaudichaudii Trécul (EBGT), previously standardized by LC-MS. However, the exceptionally low water solubility of these psoralens can cause incomplete and variable bioavailability limiting their applications and patient adherence to treatment. Therefore, the purpose of this work was to investigate the effects of 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) inclusion complex on the solubility and jejunal permeability of PSO and 5-MOP from EBGT. Characterization of inclusion complexes were evaluated by current methods in nuclear magnetic resonance studies on aqueous solution, Fourier transform infrared spectroscopy, thermal analysis, and scanning electron microscopy in solid state. Ex vivo rat jejunal permeability was also investigated and compared for both pure psoralens and plant extract formulation over a wide HP-ß-CD concentration range (2.5 to 70 mM). Phase solubility studies of the PSO- and 5-MOP-HP-ß-CD inclusion complex showed 1:1 inclusion complex formation with small stability constants (Kc < 500 M−1). PSO and 5-MOP permeability rate decreased after adding HP-ß-CD by 6- and 4-fold for pure standards and EBGT markers, respectively. Nevertheless, the complexation with HP-ß-CD significantly improved solubility of PSO (until 10-fold) and 5-MOP (until 31-fold). As a result, the permeability drop could be overcome by solubility augmentation, implying that the HP-ß-CD inclusion complexes with PSO, 5-MOP, or EBGT can be a valuable tool for designing and developing novel oral drug product formulation containing these psoralens for the treatment of vitiligo.


Assuntos
Furocumarinas , Moraceae , Vitiligo , beta-Ciclodextrinas , 2-Hidroxipropil-beta-Ciclodextrina/química , Animais , Varredura Diferencial de Calorimetria , Permeabilidade , Extratos Vegetais/farmacologia , Ratos , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , beta-Ciclodextrinas/química
5.
J Biol Chem ; 295(15): 5012-5021, 2020 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-32139511

RESUMO

ß-Mannanases from the glycoside hydrolase 26 (GH26) family are retaining hydrolases that are active on complex heteromannans and whose genes are abundant in rumen metagenomes and metatranscriptomes. These enzymes can exhibit distinct modes of substrate recognition and are often fused to carbohydrate-binding modules (CBMs), resulting in a molecular puzzle of mechanisms governing substrate preference and mode of action that has not yet been pieced together. In this study, we recovered a novel GH26 enzyme with a CBM35 module linked to its N terminus (CrMan26) from a cattle rumen metatranscriptome. CrMan26 exhibited a preference for galactomannan as substrate and the crystal structure of the full-length protein at 1.85 Å resolution revealed a unique orientation of the ancillary domain relative to the catalytic interface, strategically positioning a surface aromatic cluster of the ancillary domain as an extension of the substrate-binding cleft, contributing to galactomannan preference. Moreover, systematic investigation of nonconserved residues in the catalytic interface unveiled that residues Tyr195 (-3 subsite) and Trp234 (-5 subsite) from distal negative subsites have a key role in galactomannan preference. These results indicate a novel and complex mechanism for substrate recognition involving spatially remote motifs, distal negative subsites from the catalytic domain, and a surface-associated aromatic cluster from the ancillary domain. These findings expand our molecular understanding of the mechanisms of substrate binding and recognition in the GH26 family and shed light on how some CBMs and their respective orientation can contribute to substrate preference.


Assuntos
Mananas/metabolismo , Manosidases/química , Manosidases/metabolismo , Metagenoma , Mutação , Rúmen/metabolismo , Sequência de Aminoácidos , Animais , Catálise , Domínio Catalítico , Bovinos , Cristalografia por Raios X , Galactose/análogos & derivados , Hidrólise , Manosidases/genética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Filogenia , Ligação Proteica , Homologia de Sequência , Especificidade por Substrato
6.
Cytogenet Genome Res ; 160(5): 225-237, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32659775

RESUMO

Loss of chromosome Y (LOY) is a mosaic aneuploidy that can be detected mainly in blood samples of male individuals. Usually, LOY occurrence increases with chronological age in healthy men. Moreover, recently LOY has been reported in association with several diseases, such as cancer, where its frequency is even higher. The Y chromosome is one of the shortest chromosomes of the human karyotype, and it is crucial for correct male development. This chromosome has functions beyond the male reproductive system, and loss of its genes or even LOY can have consequences for the male body that are yet to be elucidated. Analyses of the Y chromosome are largely applied in forensic contexts such as paternity testing, ancestry studies, and sexual assault cases, among others. Thus, LOY can be a disadvantage, limiting laboratory methods and result interpretation. However, as an advantage, LOY detection could be used as a biological age biomarker due to its association with the aging process. The potential application of LOY as biomarker highlights the necessity to clarify the molecular mechanism behind its occurrence and its possible applications in both health and forensic studies.


Assuntos
Aneuploidia , Cromossomos Humanos Y/genética , Medicina Legal , Marcadores Genéticos/genética , Saúde , Mosaicismo , Envelhecimento/genética , Haplótipos/genética , Humanos , Masculino , Paternidade , Delitos Sexuais
7.
Future Oncol ; 16(18): 1245-1255, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32422075

RESUMO

Aim: Analysis of the genetic hTERT-1327 C>T (rs2735940) influence on leukocyte telomere length (LTL) and tumor development, progression and overall survival in renal cell carcinoma (RCC) patients. Materials & methods: Using leukocyte DNA of RCC patients and healthy individuals, LTL measurement and allelic discrimination of rs2735940 was performed by real-time PCR. Results: RCC patients showed shorter LTL than healthy individuals and LTL increased with clinical stage. CC+TC genotypes healthy carriers' presented shorter LTL. However, no statistical association between the different genotypes and RCC risk. Nevertheless, CC homozygous presented a reduced time to disease progression and a lower overall survival. The use of hTERT-1327 single nucleotide polymorphism information increased the capacity to predict risk for RCC progression. Conclusion: In fact, in healthy individuals, hTERT-1327 CC+TC genotypes were associated with shorter LTL, and this single nucleotide polymorphism was associated with time to disease progression, being a promising potential prognosis biomarker to be used in the future.


Assuntos
Carcinoma de Células Renais/genética , Carcinoma de Células Renais/mortalidade , Neoplasias Renais/genética , Neoplasias Renais/mortalidade , Leucócitos/metabolismo , Polimorfismo de Nucleotídeo Único , Telomerase/genética , Adulto , Idoso , Biomarcadores Tumorais , Carcinoma de Células Renais/patologia , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença , Humanos , Neoplasias Renais/patologia , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , Modelos de Riscos Proporcionais , Homeostase do Telômero
8.
Nanomedicine ; 24: 102137, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31857182

RESUMO

Anaplasmosis is one of the most prevalent tick-borne diseases of cattle caused by Anaplasma marginale. MSP1a surface protein has been shown to be involved in eliciting immunity to infected cattle. Carbon nanotubes (CNTs) has been increasingly highlighted due to their needle like structure, which contain multiple attachment sites for biomolecules and may interact with or cross biological membranes, increasing antigen availability to immune system. Here, we have successfully designed a nanocomplex of a synthetic peptide noncovalently attached to multiwalled CNT (MWCNT). Peptide comprising the core motif of the MSP1a was efficiently adsorb onto the nanoparticle surface. The MWCNT-Am1 nanocomplex exhibited high stability and good dispersibility and in vivo immunization showed high levels of IgG1 and IgG2a, followed by increased expression of pro-inflammatory and anti-inflammatory cytokines. This is a proof-of-concept of a nanovaccine that was able to generate a strong immune response compared to the common antigen-adjuvant vaccine without the nanoparticles.


Assuntos
Anaplasmose/imunologia , Antígenos de Bactérias/imunologia , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/imunologia , Nanotubos de Carbono/química , Células Th1/imunologia , Células Th2/imunologia , Anaplasma/imunologia , Anaplasma/patogenicidade , Anaplasmose/prevenção & controle , Animais , Antígenos de Bactérias/química , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase
9.
Int J Mol Sci ; 21(13)2020 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-32610589

RESUMO

The tumor microenvironment has gained a lot of attention from the scientific community since it has a proven impact in the development of tumor progression and metastasis. Extracellular vesicles (EVs) are now considered one of the key players of tumor microenvironment modulation. Clear cell renal cell carcinoma (ccRCC) is the most lethal urological neoplasia and presents a high metastatic potential, which reinforces the need for the development of more effective predictive biomarkers. Our goal was to evaluate the applicability of EV-derived matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) as prognostic biomarkers for ccRCC. To do so, we studied the plasma EV content of 32 patients with localized ccRCC and 29 patients with metastatic ccRCC. We observed that patients with localized disease and tumors larger than 7 cm presented higher levels of plasma EV-derived TIMP-1 mRNA when compared with patients presenting smaller tumors (p = 0.020). Moreover, patients with metastatic disease presented higher levels of EV-derived TIMP-1 mRNA when compared with patients with localized disease (p = 0.002) and when we stratified those patients in high and low levels of TIMP-1 EV-derived mRNA, the ones presenting higher levels had a lower overall survival (p = 0.030). EV-derived TIMP-1 mRNA may be a good prognostic biomarker candidate for ccRCC.


Assuntos
Carcinoma de Células Renais/genética , Inibidor Tecidual de Metaloproteinase-1/genética , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/sangue , Carcinoma de Células Renais/metabolismo , Carcinoma de Células Renais/patologia , Vesículas Extracelulares/patologia , Feminino , Humanos , Neoplasias Renais/patologia , Masculino , Metaloproteinase 2 da Matriz/genética , Metaloproteinases da Matriz/genética , Metaloproteinases da Matriz/metabolismo , Projetos Piloto , Plasma , Prognóstico , RNA Mensageiro/genética , Inibidor Tecidual de Metaloproteinase-1/análise , Inibidor Tecidual de Metaloproteinase-2/genética , Inibidores Teciduais de Metaloproteinases/genética , Inibidores Teciduais de Metaloproteinases/metabolismo , Microambiente Tumoral/genética , Microambiente Tumoral/fisiologia
10.
J Biol Chem ; 293(35): 13636-13649, 2018 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-29997257

RESUMO

The classical microbial strategy for depolymerization of ß-mannan polysaccharides involves the synergistic action of at least two enzymes, endo-1,4-ß-mannanases and ß-mannosidases. In this work, we describe the first exo-ß-mannanase from the GH2 family, isolated from Xanthomonas axonopodis pv. citri (XacMan2A), which can efficiently hydrolyze both manno-oligosaccharides and ß-mannan into mannose. It represents a valuable process simplification in the microbial carbon uptake that could be of potential industrial interest. Biochemical assays revealed a progressive increase in the hydrolysis rates from mannobiose to mannohexaose, which distinguishes XacMan2A from the known GH2 ß-mannosidases. Crystallographic analysis indicates that the active-site topology of XacMan2A underwent profound structural changes at the positive-subsite region, by the removal of the physical barrier canonically observed in GH2 ß-mannosidases, generating a more open and accessible active site with additional productive positive subsites. Besides that, XacMan2A contains two residue substitutions in relation to typical GH2 ß-mannosidases, Gly439 and Gly556, which alter the active site volume and are essential to its mode of action. Interestingly, the only other mechanistically characterized mannose-releasing exo-ß-mannanase so far is from the GH5 family, and its mode of action was attributed to the emergence of a blocking loop at the negative-subsite region of a cleft-like active site, whereas in XacMan2A, the same activity can be explained by the removal of steric barriers at the positive-subsite region in an originally pocket-like active site. Therefore, the GH2 exo-ß-mannanase represents a distinct molecular route to this rare activity, expanding our knowledge about functional convergence mechanisms in carbohydrate-active enzymes.


Assuntos
Proteínas de Bactérias/metabolismo , Xanthomonas/metabolismo , beta-Manosidase/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Domínio Catalítico , Cristalografia por Raios X , Hidrólise , Cinética , Mananas/metabolismo , Manose/metabolismo , Modelos Moleculares , Conformação Proteica , Espalhamento a Baixo Ângulo , Alinhamento de Sequência , Especificidade por Substrato , Difração de Raios X , Xanthomonas/química , Xanthomonas/enzimologia , beta-Manosidase/química
11.
Biotechnol Bioeng ; 116(4): 734-744, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30556897

RESUMO

Rational design is an important tool for sculpting functional and stability properties of proteins and its potential can be much magnified when combined with in vitro and natural evolutionary diversity. Herein, we report the structure-guided design of a xylose-releasing exo-ß-1,4-xylanase from an inactive member of glycoside hydrolase family 43 (GH43). Structural analysis revealed a nonconserved substitution (Lys247 ) that results in the disruption of the hydrogen bond network that supports catalysis. The mutation of this residue to a conserved serine restored the catalytic activity and crystal structure elucidation of the mutant confirmed the recovery of the proper orientation of the catalytically relevant histidine. Interestingly, the tailored enzyme can cleave both xylooligosaccharides and xylan, releasing xylose as the main product, being the first xylose-releasing exo-ß-1,4-xylanase reported in the GH43 family. This enzyme presents a unique active-site topology when compared with closely related ß-xylosidases, which is the absence of a hydrophobic barrier at the positive-subsite region, allowing the accommodation of long substrates. Therefore, the combination of rational design for catalytic activation along with naturally occurring differences in the substrate binding interface led to the discovery of a novel activity within the GH43 family. In addition, these results demonstrate the importance of solvation of the ß-propeller hollow for GH43 catalytic function and expand our mechanistic understanding about the diverse modes of action of GH43 members, a key and polyspecific carbohydrate-active enzyme family abundant in most plant cell-wall-degrading microorganisms.


Assuntos
Bacillus licheniformis/enzimologia , Xilose/metabolismo , Xilosidases/genética , Xilosidases/metabolismo , Bacillus licheniformis/química , Bacillus licheniformis/genética , Bacillus licheniformis/metabolismo , Domínio Catalítico , Cristalografia por Raios X , Ativação Enzimática , Ligação de Hidrogênio , Modelos Moleculares , Mutagênese Sítio-Dirigida , Conformação Proteica , Multimerização Proteica , Especificidade por Substrato , Xilosidases/química
12.
Future Oncol ; 15(20): 2361-2370, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31267758

RESUMO

Aim: The majority of clear cell renal cell carcinoma patients develop resistance to mTOR inhibitors. Materials & methods: As an in vitro model four cell lines were used: HKC-8, 786- O, RCC-FG-2 and an everolimus-resistant cell line (786-OR) established during this study. The quantification of miRNA-101 and HIF-2α mRNA levels was assessed by real-time PCR. Results: We observed a significant decrease of miRNA-101 intracellular levels in 786-OR. However, this miRNA presented higher extracellular levels. Additionally, we found a significant increase of HIF-2α in 786-OR. Conclusion: The circulating levels of miRNA-101 may be a potential biomarker of anti-mTOR therapy response and resistance prediction. Moreover, the resistance to mTOR inhibitors seems to be related with the overexpression of HIF-2α.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Carcinoma de Células Renais/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/genética , Everolimo/farmacologia , Neoplasias Renais/tratamento farmacológico , MicroRNAs/metabolismo , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/patologia , Linhagem Celular Tumoral , Everolimo/uso terapêutico , Humanos , Neoplasias Renais/genética , Neoplasias Renais/patologia , MicroRNAs/sangue , Serina-Treonina Quinases TOR/antagonistas & inibidores
13.
J Biol Chem ; 292(17): 7023-7039, 2017 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-28292930

RESUMO

Leishmania parasites have evolved a number of strategies to cope with the harsh environmental changes during mammalian infection. One of these mechanisms involves the functional gain that allows mitochondrial 2-Cys peroxiredoxins to act as molecular chaperones when forming decamers. This function is critical for parasite infectivity in mammals, and its activation has been considered to be controlled exclusively by the enzyme redox state under physiological conditions. Herein, we have revealed that magnesium and calcium ions play a major role in modulating the ability of these enzymes to act as molecular chaperones, surpassing the redox effect. These ions are directly involved in mitochondrial metabolism and participate in a novel mechanism to stabilize the decameric form of 2-Cys peroxiredoxins in Leishmania mitochondria. Moreover, we have demonstrated that a constitutively dimeric Prx1m mutant impairs the survival of Leishmania under heat stress, supporting the central role of the chaperone function of Prx1m for Leishmania parasites during the transition from insect to mammalian hosts.


Assuntos
Cálcio/metabolismo , Leishmania/metabolismo , Magnésio/metabolismo , Proteínas Mitocondriais/metabolismo , Peroxirredoxinas/metabolismo , Proteínas de Protozoários/metabolismo , Anisotropia , Cromatografia , Dissulfetos/química , Fluorometria , Regulação da Expressão Gênica , Proteínas de Homeodomínio/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Luz , Mitocôndrias/metabolismo , Chaperonas Moleculares/metabolismo , Mutagênese Sítio-Dirigida , Oxirredução , Oxigênio/química , Multimerização Proteica , Espalhamento de Radiação , Temperatura
14.
Biochim Biophys Acta Proteins Proteom ; 1866(4): 569-579, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29454992

RESUMO

The Amazon region holds most of the biological richness of Brazil. Despite their ecological and biotechnological importance, studies related to microorganisms from this region are limited. Metagenomics leads to exciting discoveries, mainly regarding non-cultivable microorganisms. Herein, we report the discovery of a novel ß-glucosidase (glycoside hydrolase family 1) gene from a metagenome from Lake Poraquê in the Amazon region. The gene encodes a protein of 52.9 kDa, named AmBgl-LP, which was recombinantly expressed in Escherichia coli and biochemically and structurally characterized. Although AmBgl-LP hydrolyzed the synthetic substrate p-nitrophenyl-ß-d-glucopyranoside (pNPßG) and the natural substrate cellobiose, it showed higher specificity for pNPßG (kcat/Km = 6 s-1·mM-1) than cellobiose (kcat/Km = 0.6 s-1·mM-1). AmBgl-LP showed maximum activity at 40 °C and pH 6.0 when pNPßG was used as the substrate. Glucose is a competitive inhibitor of AmBgl-LP, presenting a Ki of 14 mM. X-ray crystallography and Small Angle X-ray Scattering were used to determine the AmBgl-LP three-dimensional structure and its oligomeric state. Interestingly, despite sharing similar active site architecture with other structurally characterized GH1 family members which are monomeric, AmBgl-LP forms stable dimers in solution. The identification of new GH1 members by metagenomics might extend our understanding of the molecular mechanisms and diversity of these enzymes, besides enabling us to survey their industrial applications.


Assuntos
Lagos/microbiologia , Metagenoma , Microbiologia da Água , beta-Glucosidase/química , Brasil , beta-Glucosidase/genética , beta-Glucosidase/metabolismo
15.
Biochim Biophys Acta Gen Subj ; 1861(9): 2175-2185, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28579513

RESUMO

BACKGROUND: Warburg Effect is a metabolic switch that occurs in most of cancer cells but its advantages are not fully understood. This switch is known to happen in renal cell carcinoma (RCC), which is the most common solid cancer of the adult kidney. RCC carcinogenesis is related to pVHL loss and Hypoxia Inducible Factor (HIF) activation, ultimately leading to the activation of several genes related to glycolysis. MicroRNAs (miRNAs) regulate gene expression at a post-transcriptional level and are also deregulated in several cancers, including RCC. SCOPE OF REVIEW: This review focuses in the miRNAs that direct target enzymes involved in glycolysis and that are deregulated in several cancers. It also reviews the possible application of miRNAs in the improvement of clinical patients' management. MAJOR CONCLUSIONS: Several miRNAs that direct target enzymes involved in glycolysis are downregulated in cancer, strongly influencing the Warburg Effect. Due to this strong influence, FDG-PET can possibly benefit from measurement of these miRNAs. Restoring their levels can also bring an improvement to the current therapies. GENERAL SIGNIFICANCE: Despite being known for almost a hundred years, the Warburg Effect is not fully understood. MiRNAs are now known to be intrinsically connected with this effect and present an opportunity to understand it. They also open a new door to improve current diagnosis and prognosis tests as well as to complement current therapies. This is urgent for cancers like RCC, mostly due to the lack of an efficient screening test for early relapse detection and follow-up and the development of resistance to current therapies.


Assuntos
Carcinoma de Células Renais/metabolismo , Glicólise , Neoplasias Renais/metabolismo , MicroRNAs/fisiologia , Aerobiose , Biomarcadores , Ciclo do Ácido Cítrico , Fluordesoxiglucose F18 , Regulação Neoplásica da Expressão Gênica , Transportador de Glucose Tipo 1/fisiologia , Transportador de Glucose Tipo 4/fisiologia , Humanos , Tomografia por Emissão de Pósitrons
16.
J Perinat Med ; 45(3): 327-332, 2017 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-27564692

RESUMO

OBJECTIVE: The aim of this study was to explore whether linear and non-linear analysis of uterine contraction (UC) signals obtained with external tocodynamometry can predict operative vaginal delivery (OVD). MATERIALS AND METHODS: The last 2 h before delivery (H1 and H2) of 55 UC recordings acquired with external tocodynamometry in the labour ward of a tertiary care hospital were analysed. Signal processing involved the quantification of UCs/segment (UCN), and the linear and non-linear indices: Sample Entropy (SampEn) measuring signal irregularity; interval index (II) measuring signal variability, both of which may be associated with uterine muscle fatigue, and high frequency (HF), associated with maternal breathing movements. Thirty-two women had normal deliveries and 23 OVDs. Statistical inference was performed using 95% confidence intervals (95% CIs) for the median, and areas under the receiver operating curves (auROCs), with univariate and bivariate analyses. RESULTS: A significant association was found between maternal body mass index (BMI) and UC signal quality in H1, with moderate/poor signal quality being more frequent with higher maternal BMI. There was an overall increase in contraction frequency (UCN), signal regularity (SampEn), signal variability (II), and maternal breathing (HF) from H1 to H2. The OVD group exhibited significantly higher values of signal irregularity and variability (SampEn and II) in H1, and higher contraction frequency (UCN) and maternal breathing (HF) in H2. Modest auROCs were obtained with these indices in the discrimination between normal and OVDs. CONCLUSIONS: The results of this exploratory study suggest that analysis of UC signals obtained with tocodynamometry, using linear and non-linear indices associated with muscle fatigue and maternal breathing, identifies significant changes occurring during labour, and differences between normal and OVDs, but their discriminative capacity between the two types of delivery is modest. Further refinement of this analysis is needed before it may be clinically useful.


Assuntos
Parto Obstétrico , Contração Uterina , Monitorização Uterina/estatística & dados numéricos , Adulto , Feminino , Humanos , Recém-Nascido , Modelos Lineares , Masculino , Dinâmica não Linear , Portugal , Valor Preditivo dos Testes , Gravidez , Processamento de Sinais Assistido por Computador , Adulto Jovem
17.
J Biol Chem ; 290(13): 8582-90, 2015 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-25666622

RESUMO

2-Cys peroxiredoxins belonging to the Prx1 subfamily are Cys-based peroxidases that control the intracellular levels of H2O2 and seem to assume a chaperone function under oxidative stress conditions. The regulation of their peroxidase activity as well as the observed functional switch from peroxidase to chaperone involves changes in their quaternary structure. Multiple factors can modulate the oligomeric transitions of 2-Cys peroxiredoxins such as redox state, post-translational modifications, and pH. However, the molecular basis for the pH influence on the oligomeric state of these enzymes is still elusive. Herein, we solved the crystal structure of a typical 2-Cys peroxiredoxin from Leishmania in the dimeric (pH 8.5) and decameric (pH 4.4) forms, showing that conformational changes in the catalytic loop are associated with the pH-induced decamerization. Mutagenesis and biophysical studies revealed that a highly conserved histidine (His(113)) functions as a pH sensor that, at acidic conditions, becomes protonated and forms an electrostatic pair with Asp(76) from the catalytic loop, triggering the decamerization. In these 2-Cys peroxiredoxins, decamer formation is important for the catalytic efficiency and has been associated with an enhanced sensitivity to oxidative inactivation by overoxidation of the peroxidatic cysteine. In eukaryotic cells, exposure to high levels of H2O2 can trigger intracellular pH variations, suggesting that pH changes might act cooperatively with H2O2 and other oligomerization-modulator factors to regulate the structure and function of typical 2-Cys peroxiredoxins in response to oxidative stress.


Assuntos
Peroxidases/química , Proteínas de Protozoários/química , Domínio Catalítico , Cristalografia por Raios X , Concentração de Íons de Hidrogênio , Leishmania braziliensis/enzimologia , Mitocôndrias/enzimologia , Modelos Moleculares , Multimerização Proteica , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína
18.
Cranio ; 33(3): 211-6, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25027731

RESUMO

AIMS: The aim of this study was to investigate the relationship between occlusal factors and temporomandibular disorders (TMD). METHODOLOGY: One hundred patients were selected among those who sought medical or dental care in public practice in Recife, Brazil. The presence of malocclusions and absence of five or more posterior teeth were evaluated by the clinical exam. TMD diagnosis was given using Research Diagnostic Criteria (RDC/TMD). Statistics were carried out using Fisher and Mann-Whitney methods with 5% significance level, as well as multiple logistic regression analysis. RESULTS: The sample was mainly comprised of women (83%), individuals over 30 years old (57%) and singles (53%). The percentage of TMD and malocclusion in total sample was 42% and 50%, respectively, while in TMD subjects, malocclusion was present in 38.1%. There was no association between TMD and the occlusal factors studied. CONCLUSION: It can be concluded that malocclusion and loss of five or more posterior teeth does not contribute to TMD.


Assuntos
Má Oclusão/complicações , Transtornos da Articulação Temporomandibular/etiologia , Perda de Dente/complicações , Adolescente , Adulto , Idoso , Brasil/epidemiologia , Feminino , Humanos , Masculino , Má Oclusão/epidemiologia , Pessoa de Meia-Idade , Transtornos da Articulação Temporomandibular/epidemiologia , Perda de Dente/epidemiologia
19.
Med Oral Patol Oral Cir Bucal ; 19(3): e232-6, 2014 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-24316706

RESUMO

OBJECTIVE: To analyze the influence of socioeconomic and demographic factors (gender, economic class, age and marital status) on the occurrence of temporomandibular disorder. STUDY DESIGN: One hundred individuals from urban areas in the city of Recife (Brazil) registered at Family Health Units was examined using Axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) which addresses myofascial pain and joint problems (disc displacement, arthralgia, osteoarthritis and oesteoarthrosis). The Brazilian Economic Classification Criteria (CCEB) was used for the collection of socioeconomic and demographic data. Then, it was categorized as Class A (high social class), Classes B/C (middle class) and Classes D/E (very poor social class). The results were analyzed using Pearson's chi-square test for proportions, Fisher's exact test, nonparametric Mann-Whitney test and Binary logistic regression analysis. RESULTS: None of the participants belonged to Class A, 72% belonged to Classes B/C and 28% belonged to Classes D/E. The multivariate analysis revealed that participants from Classes D/E had a 4.35-fold greater chance of exhibiting myofascial pain and 11.3-fold greater chance of exhibiting joint problems. CONCLUSION: Poverty is a important condition to exhibit myofascial pain and joint problems.


Assuntos
Transtornos da Articulação Temporomandibular/epidemiologia , Adolescente , Adulto , Idoso , Brasil/epidemiologia , Demografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Fatores de Risco , Fatores Socioeconômicos , Adulto Jovem
20.
Biochim Biophys Acta Rev Cancer ; 1879(2): 189067, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38160898

RESUMO

Prostate cancer (PC) is the second most frequently diagnosed cancer and the fifth leading cause of cancer-related deaths in male population worldwide. Since the growth and progression of PC highly depend on the androgen pathway, androgen deprivation therapy (ADT) is the mainstay of systemic treatment. Enzalutamide is a second-generation antiandrogen, which is widely used for the treatment of advanced and metastatic PC. However, treatment failure and disease progression, caused by the emergence of enzalutamide resistant phenotypes, remains an important clinical challenge. MicroRNAs (miRNAs) are key regulators of gene expression and have recently emerged as potential biomarkers for being stable and easily analysed in several biological fluids. Several miRNAs that exhibit dysregulated expression patterns in enzalutamide-resistant PC have recently been identified, including miRNAs that modulate critical signalling pathways and genes involved in PC growth, survival and in the acquisition of enzalutamide phenotype. The understanding of molecular mechanisms by which miRNAs promote the development of enzalutamide resistance can provide valuable insights into the complex interplay between miRNAs, gene regulation, and treatment response in PC. Moreover, these miRNAs could serve as valuable tools for monitoring treatment response and disease progression during enzalutamide administration. This review summarises the miRNAs associated with enzalutamide resistance in PC already described in the literature, focusing on their biological roles and on their potential as biomarkers.


Assuntos
Benzamidas , MicroRNAs , Nitrilas , Feniltioidantoína , Neoplasias de Próstata Resistentes à Castração , Humanos , Masculino , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/genética , Neoplasias de Próstata Resistentes à Castração/patologia , Antagonistas de Androgênios/uso terapêutico , MicroRNAs/genética , MicroRNAs/uso terapêutico , Androgênios , Biomarcadores , Progressão da Doença
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