RESUMO
BACKGROUND: Malnutrition and accessible high-quality protein food sources are two of the world's alimentary challenges. Edible insects are nowadays recognized as a possible functional food solution with lower environmental impacts and beneficial health effects. OBJECTIVE: In this context, the aim of the present study is to evaluate Madagascar cockroach (Gromphadorhina portentosa) flour supplementation effects on a malnourished mice model, considering its effects on metabolism, adiposity, and inflammatory liver profiles. METHOD: Male Swiss mice are divided into five groups and fed with experimental diets for eight weeks, including a standard diet (ST) ad libitum, AIN93 ad libitum (AIN), insect flour-enriched AIN93 (AIN+IM), AIN-40% feed restriction (AIN-FR), and insect flour-enriched AIN-40% of feed restriction (AIN-FR+IM). The metabolic profiles, adipose tissue, biochemical parameters, and liver IL-6 and IL-10 expression are evaluated. RESULTS: The main findings show a body weight and metabolism improvement followed by an increased recovery of the adipocyte area in the AIN-FR+IM group when compared to the AIN-FR malnourished group. Reduced hepatic IL-6 and increased IL-10 expression are also detected in the AIN-FR+IM group. CONCLUSION: The results show that insect flour supplementation enhances both body weight and adiposity gain/recovery. The results also show hepatic improvement of inflammatory markers.
Assuntos
Baratas , Desnutrição , Animais , Dieta , Suplementos Nutricionais , Farinha , Fígado , Madagáscar , Masculino , Camundongos , Patentes como AssuntoRESUMO
It is urgent the transition from a fossil fuel-based economy to a sustainable bioeconomy based on bioconversion technologies using renewable plant biomass feedstocks to produce high chemicals, bioplastics, and biofuels. ß-Glucosidases are key enzymes responsible for degrading the plant cell wall polymers, as they cleave glucan-based oligo- and polysaccharides to generate glucose. Monosaccharide-tolerant or -stimulated ß-glucosidases have been reported in the past decade. Here, we describe a novel mechanism of ß-glucosidase stimulation by glucose and xylose. The glycoside hydrolase 1 family ß-glucosidase from Thermotoga petrophila (TpBgl1) displays a typical glucose stimulation mechanism based on an increased Vmax and decreased Km in response to glucose. Through molecular docking and dynamics analyses, we mapped putative monosaccharide binding regions (BRs) on the surface of TpBgl1. Our results indicate that after interaction with glucose or xylose at BR1 site, an adjacent loop region assumes an extended conformation, which increases the entrance to the TpBgl1 active site, improving product formation. Biochemical assays with TpBgl1 BR1 mutants, TpBgl1D49A/Y410A and TpBgl1D49K/Y410H, resulted in decreasing and abolishing monosaccharide stimulation, respectively. These mutations also impaired the BR1 looping extension responsible for monosaccharide stimulation. This study provides a molecular basis for the rational design of ß-glucosidases for biotechnological applications.
Assuntos
Monossacarídeos/metabolismo , Thermotoga/enzimologia , beta-Glucosidase/química , beta-Glucosidase/metabolismo , Biocatálise , Domínio Catalítico , Glucose/metabolismo , Cinética , Simulação de Dinâmica Molecular , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Ligação Proteica , Conformação Proteica , Xilose/metabolismoRESUMO
A bioreactor was built by means of immobilizing alpha-amylase from Aspergillus oryzae by encapsulation, through cryopolymerization of acrylamide monomers for the continuous starch hydrolysis. The starch hydrolysis was evaluated regarding pH, the concentration of immobilized amylase on cryogel, the concentration of starch solution and temperature. The maximum value for starch hydrolysis was achieved at pH 5.0, concentration of immobilized enzyme 111.44 mg amylase /gcryogel , concentration of starch solution 45 g/L and temperature of 35°C. The immobilized enzyme showed a conversion ratio ranging from 68.2 to 97.37%, depending on the pH and temperature employed. Thus, our results suggest that the alpha-amylase from A. oryzae immobilized on cryogel monoliths represents a potential process for industrial production of maltose from starch hydrolysis.
Assuntos
Reatores Biológicos , Criogéis/química , Enzimas Imobilizadas/metabolismo , Amido/metabolismo , alfa-Amilases/metabolismo , Aspergillus oryzae , Enzimas Imobilizadas/química , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Maltose/metabolismo , Porosidade , Amido/análise , Amido/química , Temperatura , alfa-Amilases/químicaRESUMO
BACKGROUND: The renin-angiotensin system (RAS) is an important enzymatic system responsible for the regulation of biological functions, such as the arterial pressure, hydroelectrolytic control, vascular vasodilatation/vasoconstriction and more recently metabolic functions. OBJECTIVES: The aim of the present review is to discuss the associations between the gut microbiome and the renin-angiotensin system and the influence of their intimate relationship on the cardiovascular health. METHODS: A literature review of the main studies published regarding the relationship among the renin-angiotensin system, gut microbiota and cardiovascular health was performed. RESULTS: The association between the ACE2 and gut microbiota has been discussed. It is shown that the ACE2/Ang 1-7 axis modulates the immune response, influencing the microbiota composition, and thus being one of the causes for some diseases physiophatologies, such as diarrhea and intestinal inflammatory disease. CONCLUSION: The association between RAS and gut microbiota seems to have a strong influence on the genesis of cardiovascular diseases, through direct mechanisms, such as nerve stimulation, or indirectly on metabolic parameters, such as weight, adiposity and lipid profile.
Assuntos
Angiotensina I/metabolismo , Doenças Cardiovasculares/metabolismo , Doenças Cardiovasculares/microbiologia , Microbioma Gastrointestinal/imunologia , Fragmentos de Peptídeos/metabolismo , Peptidil Dipeptidase A/metabolismo , Sistema Renina-Angiotensina/imunologia , Enzima de Conversão de Angiotensina 2 , Animais , Doenças Cardiovasculares/tratamento farmacológico , Doenças Cardiovasculares/imunologia , HumanosRESUMO
BACKGROUND: During the past few years, the first industrial-scale cellulosic ethanol plants have been inaugurated. Although the performance of the commercial cellulase enzymes used in this process has greatly improved over the past decade, cellulases still represent a very significant operational cost. Depending on the region, transport of cellulases from a central production facility to a biorefinery may significantly add to enzyme cost. The aim of the present study was to develop a simple, cost-efficient cellulase production process that could be employed locally at a Brazilian sugarcane biorefinery. RESULTS: Our work focused on two main topics: growth medium formulation and strain improvement. We evaluated several Brazilian low-cost industrial residues for their potential in cellulase production. Among the solid residues evaluated, soybean hulls were found to display clearly the most desirable characteristics. We engineered a Trichoderma reesei strain to secrete cellulase in the presence of repressing sugars, enabling the use of sugarcane molasses as an additional carbon source. In addition, we added a heterologous ß-glucosidase to improve the performance of the produced enzymes in hydrolysis. Finally, the addition of an invertase gene from Aspegillus niger into our strain allowed it to consume sucrose from sugarcane molasses directly. Preliminary cost analysis showed that the overall process can provide for very low-cost enzyme with good hydrolysis performance on industrially pre-treated sugarcane straw. CONCLUSIONS: In this study, we showed that with relatively few genetic modifications and the right growth medium it is possible to produce considerable amounts of well-performing cellulase at very low cost in Brazil using T. reesei. With further enhancements and optimization, such a system could provide a viable alternative to delivered commercial cellulases.
RESUMO
Lipogenesis is the process by which fatty acids are synthesized. In metabolic syndrome, an insulin resistant state along with high plasma levels of free fatty acids (FFA) and hyperglycemia may contribute to the lipogenic process. The aim of the present study was to investigate the effects of oral administration of metformin on the expression of lipogenic genes and glycemic profile in mice fed with low-carbohydrate high-fat diet by evaluating their metabolic profile. SWISS male mice were divided into 4 groups (N = 7) that were fed with standard (ST), standard plus metformin (ST + MET), low-carbohydrate high-fat diet (LCHFD) and low-carbohydrate high-fat diet plus metformin (LCHFD + MET) (100 mg kg-1 diet) diets respectively. Food intake, body weight and blood parameters, such as glucose tolerance, insulin sensitivity, glucose, HDL-c, total cholesterol, triglycerides, ASL and ALT levels were assessed. Histological analyses were performed on hematoxylin and eosin-stained epididymal adipose tissue histological specimens. The expression levels of peroxisome proliferator-activated receptor (PPARγ), sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC), were assessed by RT-PCR. This study showed that metformin decreased adipocyte area, body weight and food consumption in obese animals when compared to the standard group. Furthermore, the expression of lipogenic markers in adipose tissue were diminished in obese animals treated with metformin. This data showed that oral administration of metformin improved glucose and lipid metabolic parameters in white adipose tissue by reducing the expression of lipogenesis markers, suggesting an important clinical application of MET in treating obesity-related diseases in metabolic syndrome.
Assuntos
Biomarcadores/sangue , Hipoglicemiantes/administração & dosagem , Lipogênese/efeitos dos fármacos , Metformina/administração & dosagem , Obesidade/metabolismo , Acetil-CoA Carboxilase/genética , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Administração Oral , Animais , Peso Corporal/efeitos dos fármacos , Dieta com Restrição de Carboidratos , Dieta Hiperlipídica , Ingestão de Alimentos/efeitos dos fármacos , Ácido Graxo Sintases/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Hipoglicemiantes/farmacologia , Masculino , Metformina/farmacologia , Camundongos , Camundongos Obesos , Obesidade/genética , PPAR gama/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/genéticaRESUMO
Xylanases catalyze the hydrolysis of ß-1,4-linked xylosyl moieties from xylan chains, one of the most abundant hemicellulosic polysaccharides found in plant cell walls. These enzymes can exist either as single catalytic domains or as modular proteins composed of one or more carbohydrate-binding modules (CBMs) appended to the catalytic core. However, the molecular mechanisms governing the synergistic effects between catalytic domains and their CBMs are not fully understood. Thus, the goal of this study was to evaluate the functional effects of the fusion of a CBM belonging to family 6, which exhibits high affinity to xylan, with the GH11 xylanase from Bacillus subtilis, which does not have a CBM in its wild-type form. The wild-type enzyme (BsXyl11) and the chimeric protein (BsXyl11-CBM6) were heterologously produced in Escherichia coli and purified to homogeneity for biochemical characterization. The molecular fusion did not alter the pH and temperature dependence, but kinetic data revealed an increase of 65% in the catalytic efficiency of the chimeric enzyme. Furthermore, the BsXyl11-CBM6 chimera was used to supplement the commercial cocktail Accellerase® 1500 and improved the reducing sugar release by 17% from pretreated sugarcane bagasse. These results indicate that CBM6 can be used as a molecular tool to enhance the catalytic performance of endo-xylanases (GH11) and provide a new strategy for the development of optimized biocatalysts for biotechnological applications.
Assuntos
Endo-1,4-beta-Xilanases/química , Endo-1,4-beta-Xilanases/metabolismo , Xilanos/metabolismo , Bacillus subtilis/enzimologia , Bacillus subtilis/genética , Biotecnologia , Catálise , Domínio Catalítico , Celulose , Endo-1,4-beta-Xilanases/genética , Hidrólise , Cinética , Domínios Proteicos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Saccharum , Especificidade por Substrato , Xilanos/químicaRESUMO
Xylan is an abundant plant cell wall polysaccharide and its reduction to xylose units for subsequent biotechnological applications requires a combination of distinct hemicellulases and auxiliary enzymes, mainly endo-xylanases and ß-xylosidases. In the present work, a bifunctional enzyme consisting of a GH11 endo-1,4-ß-xylanase fused to a GH43 ß-xylosidase, both from Bacillus subtilis, was designed taking into account the quaternary arrangement and accessibility to the substrate. The parental enzymes and the resulting chimera were successfully expressed in Escherichia coli, purified and characterized. Interestingly, the substrate cleavage rate was altered by the molecular fusion improving at least 3-fold the xylose production using specific substrates as beechwood xylan and hemicelluloses from pretreated biomass. Moreover, the chimeric enzyme showed higher thermotolerance with a positive shift of the optimum temperature from 35 to 50 °C for xylosidase activity. This improvement in the thermal stability was also observed by circular dichroism unfolding studies, which seems to be related to a gain of stability of the ß-xylosidase domain. These results demonstrate the superior functional and stability properties of the chimeric enzyme in comparison to individual parental domains, suggesting the molecular fusion as a promising strategy for enhancing enzyme cocktails aiming at lignocellulose hydrolysis.
Assuntos
Glicosídeo Hidrolases/metabolismo , Xilose/biossíntese , Bacillus subtilis/enzimologia , Bacillus subtilis/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biomassa , Biotecnologia , Dicroísmo Circular , Endo-1,4-beta-Xilanases/química , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/metabolismo , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Hidrólise , Lignina/metabolismo , Modelos Moleculares , Polissacarídeos/metabolismo , Estrutura Quaternária de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Especificidade por Substrato , Temperatura , Xilanos/metabolismo , Xilosidases/química , Xilosidases/genética , Xilosidases/metabolismoRESUMO
The ß-glucosidases are enzymes essential for several industrial applications, especially in the field of plant structural polysaccharides conversion into bioenergy and bioproducts. In a recent study, we have provided a biochemical characterization of two hyperthermostable ß-glucosidases from Thermotoga petrophila belonging to the families GH1 (TpBGL1) and GH3 (TpBGL3). Here, as part of a continuing investigation, the oligomeric state, the net charge, and the structural stability, at acidic pH, of the TpBGL1 and TpBGL3 were characterized and compared. Enzymatic activity is directly related to the balance between protonation and conformational changes. Interestingly, our results indicated that there were no significant changes in the secondary, tertiary and quaternary structures of the ß-glucosidases at temperatures below 80 °C. Furthermore, the results indicated that both the enzymes are stable homodimers in solution. Therefore, the observed changes in the enzymatic activities are due to variations in pH that modify protonation of the enzymes residues and the net charge, directly affecting the interactions with ligands. Finally, the results showed that the two ß-glucosidases displayed different pH dependence of thermostability at temperatures above 80 °C. TpBGL1 showed higher stability at pH 6 than at pH 4, while TpBGL3 showed similar stability at both pH values. This study provides a useful comparison of the structural stability, at acidic pH, of two different hyperthermostable ß-glucosidases and how it correlates with the activity of the enzymes. The information described here can be useful for biotechnological applications in the biofuel and food industries.
Assuntos
Proteínas de Bactérias/química , Celulases/química , Bacilos Gram-Negativos Anaeróbios Retos, Helicoidais e Curvos/química , Prótons , Estabilidade Enzimática , Bacilos Gram-Negativos Anaeróbios Retos, Helicoidais e Curvos/enzimologia , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Multimerização Proteica , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Eletricidade Estática , TemperaturaRESUMO
Beta-glucosidases (BGLs) are enzymes of great potential for several industrial processes, since they catalyze the cleavage of glucosidic bonds in cellobiose and other short cellooligosaccharides. However, features such as good stability to temperature, pH, ions and chemicals are required characteristics for industrial applications. This work aimed to provide a comparative biochemical analysis of three thermostable BGLs from Pyrococcus furiosus and Thermotoga petrophila. The genes PfBgl1 (GH1 from P. furiosus), TpBgl1 (GH1 from T. petrophila) and TpBgl3 (GH3 from T. petrophila) were cloned and proteins were expressed in Escherichia coli. The purified enzymes are hyperthermophilic, showing highest activity at temperatures above 80°C at acidic (TpBgl3 and PfBgl1) and neutral (TpBgl1) pHs. The BGLs showed greatest stability to temperature mainly at pH 6.0. Activities using a set of different substrates suggested that TpBgl3 (GH3) is more specific than GH1 family members. In addition, the influence of six monosaccharides on BGL catalysis was assayed. While PfBgl1 and TpBgl3 seemed to be weakly inhibited by monosaccharides, TpBgl1 was activated, with xylose showing the strongest activation. Under the conditions tested, TpBgl1 showed the highest inhibition constant (Ki=1100.00mM) when compared with several BGLs previously characterized. The BGLs studied have potential for industrial use, specifically the enzymes belonging to the GH1 family, due to its broad substrate specificity and weak inhibition by glucose and other saccharides.
Assuntos
Indústrias , beta-Glucosidase/metabolismo , Análise de Variância , Biocatálise/efeitos dos fármacos , Dissacarídeos/metabolismo , Ácido Edético/farmacologia , Concentração de Íons de Hidrogênio , Hidrólise/efeitos dos fármacos , Cinética , Polissacarídeos/metabolismo , Pyrococcus furiosus/enzimologia , Especificidade por Substrato/efeitos dos fármacos , TemperaturaRESUMO
High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO.
Assuntos
Aspergillus niger/enzimologia , Proteínas Fúngicas/química , Glucose Oxidase/química , Pressão , Desnaturação Proteica , Sequência de Aminoácidos , Fracionamento Celular , Estabilidade Enzimática , Proteínas Fúngicas/metabolismo , Glucose Oxidase/metabolismo , Temperatura Alta , Cinética , Dados de Sequência Molecular , Conformação ProteicaRESUMO
Arabinanases (ABNs, EC 3.2.1.99) are promising catalysts for environmentally friendly biomass conversion into energy and chemicals. These enzymes catalyze the hydrolysis of the α-1,5-linked L-arabinofuranoside backbone of plant cell wall arabinans releasing arabino-oligosaccharides and arabinose, the second most abundant pentose in nature. In this work, new findings about the molecular mechanisms governing activation, functional differentiation, and catalysis of GH43 ABNs are presented. Biophysical, mutational, and biochemical studies with the hyperthermostable two-domain endo-acting ABN from Thermotoga petrophila (TpABN) revealed how some GH43 ABNs are activated by calcium ions via hyperpolarization of the catalytically relevant histidine and the importance of the ancillary domain for catalysis and conformational stability. On the other hand, the two GH43 ABNs from rumen metagenome, ARN2 and ARN3, presented a calcium-independent mechanism in which sodium is the most likely substituent for calcium ions. The crystal structure of the two-domain endo-acting ARN2 showed that its ability to efficiently degrade branched substrates is due to a larger catalytic interface with higher accessibility than that observed in other ABNs with preference for linear arabinan. Moreover, crystallographic characterization of the single-domain exo-acting ARN3 indicated that its cleavage pattern producing arabinose is associated with the chemical recognition of the reducing end of the substrate imposed by steric impediments at the aglycone-binding site. By structure-guided rational design, ARN3 was converted into a classical endo enzyme, confirming the role of the extended Arg(203)-Ala(230) loop in determining its action mode. These results reveal novel molecular aspects concerning the functioning of GH43 ABNs and provide new strategies for arabinan degradation.
Assuntos
Arabinose/química , Proteínas de Bactérias/metabolismo , Catálise , Glicosídeo Hidrolases/metabolismo , Bacilos Gram-Negativos Anaeróbios Retos, Helicoidais e Curvos/enzimologia , Sequência de Aminoácidos , Animais , Sítios de Ligação , Biotecnologia , Cálcio/química , Bovinos , Clonagem Molecular , Cristalografia por Raios X , Análise Mutacional de DNA , Hidrólise , Íons/química , Cinética , Ligantes , Metagenoma , Metais/química , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese , Engenharia de Proteínas , Estrutura Terciária de Proteína , Rúmen/microbiologia , Homologia de Sequência de Aminoácidos , Solventes/químicaRESUMO
Metagenomics has been widely employed for discovery of new enzymes and pathways to conversion of lignocellulosic biomass to fuels and chemicals. In this context, the present study reports the isolation, recombinant expression, biochemical and structural characterization of a novel endoxylanase family GH10 (SCXyl) identified from sugarcane soil metagenome. The recombinant SCXyl was highly active against xylan from beechwood and showed optimal enzyme activity at pH 6,0 and 45°C. The crystal structure was solved at 2.75 Å resolution, revealing the classical (ß/α)8-barrel fold with a conserved active-site pocket and an inherent flexibility of the Trp281-Arg291 loop that can adopt distinct conformational states depending on substrate binding. The capillary electrophoresis analysis of degradation products evidenced that the enzyme displays unusual capacity to degrade small xylooligosaccharides, such as xylotriose, which is consistent to the hydrophobic contacts at the +1 subsite and low-binding energies of subsites that are distant from the site of hydrolysis. The main reaction products from xylan polymers and phosphoric acid-pretreated sugarcane bagasse (PASB) were xylooligosaccharides, but, after a longer incubation time, xylobiose and xylose were also formed. Moreover, the use of SCXyl as pre-treatment step of PASB, prior to the addition of commercial cellulolytic cocktail, significantly enhanced the saccharification process. All these characteristics demonstrate the advantageous application of this enzyme in several biotechnological processes in food and feed industry and also in the enzymatic pretreatment of biomass for feedstock and ethanol production.
Assuntos
Metagenoma/genética , Saccharum/genética , Biotecnologia/métodos , Eletroforese Capilar , Endo-1,4-beta-Xilanases/metabolismo , Glucuronatos/metabolismo , Oligossacarídeos/metabolismoRESUMO
Termites can degrade up to 90% of the lignocellulose they ingest using a repertoire of endogenous and symbiotic degrading enzymes. Termites have been shown to secrete two main glycoside hydrolases, which are GH1 (EC 3.2.1.21) and GH9 (EC 3.2.1.4) members. However, the molecular mechanism for lignocellulose degradation by these enzymes remains poorly understood. The present study was conducted to understand the synergistic relationship between GH9 (CgEG1) and GH1 (CgBG1) from Coptotermes gestroi, which is considered the major urban pest of São Paulo State in Brazil. The goal of this work was to decipher the mode of operation of CgEG1 and CgBG1 through a comprehensive biochemical analysis and molecular docking studies. There was outstanding degree of synergy in degrading glucose polymers for the production of glucose as a result of the endo-ß-1,4-glucosidase and exo-ß-1,4-glucosidase degradation capability of CgEG1 in concert with the high catalytic performance of CgBG1, which rapidly converts the oligomers into glucose. Our data not only provide an increased comprehension regarding the synergistic mechanism of these two enzymes for cellulose saccharification but also give insight about the role of these two enzymes in termite biology, which can provide the foundation for the development of a number of important applied research topics, such as the control of termites as pests as well as the development of technologies for lignocellulose-to-bioproduct applications.
Assuntos
Glicosídeo Hidrolases/metabolismo , Isópteros/enzimologia , Animais , Celulose/metabolismo , Glicosídeo Hidrolases/isolamento & purificação , Cinética , Simulação de Acoplamento Molecular , Proteínas Recombinantes/isolamento & purificação , Especificidade por SubstratoRESUMO
α-l-Arabinofuranosidases (α-l-Abfases, EC 3.2.1.55) display a broad specificity against distinct glycosyl moieties in branched hemicellulose and recent studies have demonstrated their synergistic use with cellulases and xylanases for biotechnological processes involving plant biomass degradation. In this study, we examined the structural organization of the arabinofuranosidase (GH51 family) from the mesophilic Bacillus subtilis (AbfA) and its implications on function and stability. The recombinant AbfA showed to be active over a broad temperature range with the maximum activity between 35 and 50 °C, which is desirable for industrial applications. Functional studies demonstrated that AbfA preferentially cleaves debranched or linear arabinan and is an exo-acting enzyme producing arabinose from arabinoheptaose. The enzyme has a canonical circular dichroism spectrum of α/ß proteins and exhibits a hexameric quaternary structure in solution, as expected for GH51 members. Thermal denaturation experiments indicated a melting temperature of 53.5 °C, which is in agreement with the temperatureactivity curves. The mechanisms associated with the unfolding process were investigated through molecular dynamics simulations evidencing an important contribution of the quaternary arrangement in the stabilization of the ß-sandwich accessory domain and other regions involved in the formation of the catalytic interface of hexameric Abfases belonging to GH51 family.
Assuntos
Bacillus subtilis/química , Bacillus subtilis/enzimologia , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Sequência de Aminoácidos , Arabinose/metabolismo , Bacillus subtilis/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Dicroísmo Circular , Estabilidade Enzimática , Glicosídeo Hidrolases/metabolismo , Cinética , Modelos Moleculares , Simulação de Dinâmica Molecular , Polissacarídeos/metabolismo , Conformação Proteica , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Especificidade por SubstratoRESUMO
Multifunctional enzyme engineering can improve enzyme cocktails for emerging biofuel technology. Molecular dynamics through structure-based models (SB) is an effective tool for assessing the tridimensional arrangement of chimeric enzymes as well as for inferring the functional practicability before experimental validation. This study describes the computational design of a bifunctional xylanase-lichenase chimera (XylLich) using the xynA and bglS genes from Bacillus subtilis. In silico analysis of the average solvent accessible surface area (SAS) and the root mean square fluctuation (RMSF) predicted a fully functional chimera, with minor fluctuations and variations along the polypeptide chains. Afterwards, the chimeric enzyme was built by fusing the xynA and bglS genes. XylLich was evaluated through small-angle X-ray scattering (SAXS) experiments, resulting in scattering curves with a very accurate fit to the theoretical protein model. The chimera preserved the biochemical characteristics of the parental enzymes, with the exception of a slight variation in the temperature of operation and the catalytic efficiency (kcat/Km). The absence of substantial shifts in the catalytic mode of operation was also verified. Furthermore, the production of chimeric enzymes could be more profitable than producing a single enzyme separately, based on comparing the recombinant protein production yield and the hydrolytic activity achieved for XylLich with that of the parental enzymes.
Assuntos
Bacillus subtilis/enzimologia , Endo-1,4-beta-Xilanases/química , Glicosídeo Hidrolases/química , Simulação de Dinâmica Molecular , Proteínas Recombinantes de Fusão/química , Simulação por Computador , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/metabolismo , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Modelos Moleculares , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Espalhamento a Baixo ÂnguloRESUMO
Supplementation of cellulase cocktails with accessory enzymes can contribute to a higher hydrolytic capacity in releasing fermentable sugars from plant biomass. This study investigated which enzymes were complementary to the enzyme set of Trichoderma harzianum in the degradation of sugarcane bagasse. Specific activities of T. harzianum extract on different substrates were compared with the extracts of Penicillium echinulatum and Trichoderma reesei, and two commercial cellulase preparations. Complementary analysis of the secretome of T. harzianum was also used to identify which enzymes were produced during growth on pretreated sugarcane bagasse. These analyses enabled the selection of the enzymes pectinase and α-L-arabinofuranosidase (AF) to be further investigated as supplements to the T. harzianum extract. The effect of enzyme supplementation on the efficiency of sugarcane bagasse saccharification was evaluated using response surface methodology. The supplementation of T. harzianum enzymatic extract with pectinase and AF increased the efficiency of hydrolysis by up to 116%.
Assuntos
Carboidratos/biossíntese , Celulose/metabolismo , Glicosídeo Hidrolases/química , Poligalacturonase/química , Saccharum/microbiologia , Trichoderma/metabolismo , Carboidratos/química , Celulose/química , Ativação Enzimática , Hidrólise , Trichoderma/química , Trichoderma/classificaçãoRESUMO
Boto, a class II transposable element, was characterized in the Moniliophthora perniciosa genome. The Boto transposase is highly similar to plant PIF-like transposases that belong to the newest class II superfamily known as PIF/Harbinger. Although Boto shares characteristics with PIF-like elements, other characteristics, such as the transposase intron position, the position and direction of the second ORF, and the footprint, indicate that Boto belongs to a novel family of the PIF/Harbinger superfamily. Southern blot analyses detected 6-12 copies of Boto in C-biotype isolates and a ubiquitous presence among the C- and S-biotypes, as well as a separation in the C-biotype isolates from Bahia State in Brazil in at least two genotypic groups, and a new insertion in the genome of a C-biotype isolate maintained in the laboratory for 6 years. In addition to PCR amplification from a specific insertion site, changes in the Boto hybridization profile after the M. perniciosa sexual cycle and detection of Boto transcripts gave further evidence of Boto activity. As an active family in the genome of M. perniciosa, Boto elements may contribute to genetic variability in this homothallic fungus. This is the first report of a PIF/Harbinger transposon in the genome of a phytopathogenic fungus.
Assuntos
Agaricales/genética , Elementos de DNA Transponíveis , Sequência de Aminoácidos , Southern Blotting , Brasil , Análise por Conglomerados , DNA Fúngico/química , DNA Fúngico/genética , Genótipo , Dados de Sequência Molecular , Fases de Leitura Aberta , Filogenia , Reação em Cadeia da Polimerase , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
The structural polysaccharides contained in plant cell walls have been pointed to as a promising renewable alternative to petroleum and natural gas. Ferulic acid is a ubiquitous component of plant polysaccharides, which is found in either monomeric or dimeric forms and is covalently linked to arabinosyl residues. Ferulic acid has several commercial applications in food and pharmaceutical industries. The study herein introduces a novel feruloyl esterase from Aspergillus clavatus (AcFAE). Along with a comprehensive functional and biophysical characterization, the low-resolution structure of this enzyme was also determined by small-angle X-ray scattering. In addition, we described the production of phenolic compounds with antioxidant capacity from wheat arabinoxylan and sugarcane bagasse using AcFAE. The ability to specifically cleave ester linkages in hemicellulose is useful in several biotechnological applications, including improved accessibility to lignocellulosic enzymes for biofuel production.