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1.
J Agric Food Chem ; 67(19): 5587-5595, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31016980

RESUMO

Maltooligosyltrehalose synthase (MTSase) is a key enzyme in trehalose production. MTSase from Arthrobacter ramosus has poor thermostability, limiting its industrial use. In this study, mutant G415P was obtained by directed evolution and S361R/S444E was subsequently generated based on a structure analysis of the region around G415. The t1/2 of G415P and S361R/S444E at 60 °C increased by 3.0- and 3.2-fold, respectively, compared with the wild-type enzyme. A triple mutant (G415P/S361R/S444E) was obtained through a combination of the above mutants, and its t1/2 significantly increased by 19.7-fold. Kinetic and thermodynamic stability results showed that the T50 and Tm values of the triple mutant increased by 7.1 and 7.3 °C, respectively, compared with those of the wild-type enzyme. When the triple mutant was used in trehalose production, the yield reached 71.6%, higher than the 70.3% achieved with the wild-type. Thus, the mutant has a potential application for industrial trehalose production.


Assuntos
Arthrobacter/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Glucosiltransferases/química , Glucosiltransferases/genética , Sequência de Aminoácidos , Arthrobacter/química , Arthrobacter/genética , Proteínas de Bactérias/metabolismo , Evolução Molecular Direcionada , Estabilidade Enzimática , Glucosiltransferases/metabolismo , Temperatura Alta , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Alinhamento de Sequência , Especificidade por Substrato
2.
Mar Biotechnol (NY) ; 21(3): 416-429, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30874930

RESUMO

Considering the global trend in the search for alternative natural compounds with antioxidant and sun protection factor (SPF) boosting properties, bacterial carotenoids represent an opportunity for exploring pigments of natural origin which possess high antioxidant activity, lower toxicity, no residues, and no environmental risk and are readily decomposable. In this work, three pigmented bacteria from the Antarctic continent, named Arthrobacter agilis 50cyt, Zobellia laminarie 465, and Arthrobacter psychrochitiniphilus 366, were able to withstand UV-B and UV-C radiation. The pigments were extracted and tested for UV absorption, antioxidant capacity, photostability, and phototoxicity profile in murine fibroblasts (3T3 NRU PT-OECD TG 432) to evaluate their further potential use as UV filters. Furthermore, the pigments were identified by ultra-high-performance liquid chromatography-photodiode array detector-mass spectrometry (UPLC-PDA-MS/MS). The results showed that all pigments presented a very high antioxidant activity and good stability under exposure to UV light. However, except for a fraction of the A. agilis 50cyt pigment, they were shown to be phototoxic. A total of 18 different carotenoids were identified from 23 that were separated on a C18 column. The C50 carotenes bacterioruberin and decaprenoxanthin (including its variations) were confirmed for A. agilis 50cyt and A. psychrochitiniphilus 366, respectively. All-trans-bacterioruberin was identified as the pigment that did not express phototoxic activity in the 3T3 NRU PT assay (MPE < 0.1). Zeaxanthin, ß-cryptoxanthin, ß-carotene, and phytoene were detected in Z. laminarie 465. In conclusion, carotenoids identified in this work from Antarctic bacteria open perspectives for their further biotechnological application towards a more sustainable and environmentally friendly way of pigment exploitation.


Assuntos
Arthrobacter/química , Biotecnologia , Flavobacteriaceae/química , Pigmentos Biológicos/química , Regiões Antárticas , Carotenoides/química , Carotenoides/isolamento & purificação , Microbiologia Industrial , Pigmentos Biológicos/isolamento & purificação
3.
J Agric Food Chem ; 67(15): 4355-4366, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30919632

RESUMO

The crystal structure of Dextranase from the marine bacterium Arthrobacter oxidans KQ11 (Aodex) was determined at a resolution of 1.4 Å. The crystal structure of the conserved Aodex fragment (Ala52-Thr638) consisted of an N-terminal domain N and a C-terminal domain C. The N-terminal domain N was identified as a ß-sandwich, connected to a right-handed parallel ß-helix at the C-terminus. Sequence comparisons, cavity regions, and key residues of the catalytic domain analysis all suggested that the Aodex was an inverting enzyme, and the catalytic acid and base were Asp439 and Asp420, respectively. Asp440 was not a general base in the Aodex catalytic domain, and Asp396 in Dex49A may not be a general base in the catalytic domain. The thermostability of the S357F mutant using semirational design based on B-factors was clearly better than that of wild-type Aodex. This process may promote the aromatic-aromatic interactions that increase the thermostability of mutant Phe357.


Assuntos
Arthrobacter/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Dextranase/química , Dextranase/metabolismo , Arthrobacter/química , Arthrobacter/genética , Proteínas de Bactérias/genética , Catálise , Domínio Catalítico , Cristalografia por Raios X , Estabilidade Enzimática , Temperatura Alta , Modelos Moleculares
4.
Mar Drugs ; 17(3)2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30897810

RESUMO

Chondroitinase (ChSase), a type of glycosaminoglycan (GAG) lyase, can degrade chondroitin sulfate (CS) to unsaturate oligosaccharides, with various functional activities. In this study, ChSase AC II from a newly isolated marine bacterium Arthrobacter sp. CS01 was cloned, expressed in Pichia pastoris X33, purified, and characterized. ChSase AC II, with a molecular weight of approximately 100 kDa and a specific activity of 18.7 U/mg, showed the highest activity at 37 °C and pH 6.5 and maintained stability at a broad range of pH (5⁻7.5) and temperature (below 35 °C). The enzyme activity was increased in the presence of Mn2+ and was strongly inhibited by Hg2+. Moreover, the kinetic parameters of ChSase AC II against CS-A, CS-C, and HA were determined. TLC and ESI-MS analysis of the degradation products indicated that ChSase AC II displayed an exolytic action mode and completely hydrolyzed three substrates into oligosaccharides with low degrees of polymerization (DPs). All these features make ChSase AC II a promising candidate for the full use of GAG to produce oligosaccharides.


Assuntos
Organismos Aquáticos/química , Arthrobacter/química , Proteínas de Bactérias/metabolismo , Condroitina Liases/metabolismo , Sulfatos de Condroitina/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Condroitina Liases/química , Condroitina Liases/isolamento & purificação , Ensaios Enzimáticos , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Oligossacarídeos/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Temperatura Ambiente
5.
Antonie Van Leeuwenhoek ; 112(5): 711-721, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30465324

RESUMO

A wide range of bacterial species are able to induce calcium carbonate precipitation. Using our own laboratory-preserved strains, we have newly discovered that Ensifer sp. MY11e, Microbacterium sp. TMd9a1, Paeniglutamicibacter sp. MSa1a, Pseudomonas sp. GTc3, and Rheinheimera sp. ATWe6 can induce the formation of calcite crystals on an agar medium. Type strains of their closely related species (Ensifer adhaerens, Microbacterium testaceum, Paeniglutamicibacter kerguelensis, Pseudomonas protegens, and Rheinheimera texasensis) could also induce calcite formation. Although the initial pH value of the agar medium was 6.1, the pH of the agar media containing calcite, induced by cultivation of the 10 bacterial strains, increased to 8.0-8.4. The ammonification (oxidative deamination) of amino acids may been responsible for this increase in pH. The crystals formed both on and around the bacterial colonies. Furthermore, when these strains (excepting two Microbacterium strains) were cultivated on a cellulose acetate membrane filter (0.20 µm pore size) resting on the surface of the agar medium (i.e., in the membrane filter culture method), the crystals formed on the agar medium separate from the bacterial cells. These results indicate that the bacterial cells did not necessarily become nucleation sites for these crystals. We also investigated whether the studied strains could be applied to the biocementation of sand, and found that only two Ensifer strains were able to form large sand lumps.


Assuntos
Actinomycetales/metabolismo , Arthrobacter/metabolismo , Carbonato de Cálcio/metabolismo , Chromatiaceae/metabolismo , Ortópteros/metabolismo , Pseudomonas/metabolismo , Actinomycetales/química , Aminoácidos/química , Aminoácidos/metabolismo , Animais , Arthrobacter/química , Carbonato de Cálcio/química , Chromatiaceae/química , Concentração de Íons de Hidrogênio , Ortópteros/química , Oxirredução , Pseudomonas/química
6.
J Biosci ; 43(5): 941-945, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30541954

RESUMO

ß-Galactosidase is a metal-activated enzyme, which breaks down the glucosidic bond of lactose and produces glucose and galactose. Among several commercial applications, preparation of lactose-free milk has gained special attention. The present objective is to demonstrate the activity kinetics of ß-galactosidase purified from a non-pathogenic bacterium Arthrobacter oxydans SB. The enzyme was purified by DEAE-cellulose and Sephadex G-100 column chromatography. The purity of the protein was checked by high-performance liquid chromatography (HPLC). The purified enzyme of molecular weight ~95 kDa exhibited specific activity of 137.7 U mg-1 protein with a purification of 11.22-fold and yield 12.42%. The exact molecular weight (95.7 kDa) of the purified protein was determined by MALDI-TOF. Previously, most of the studies have used Mg+2 as a cofactor of ß-galactosidase. In this present investigation, we have checked the kinetic behavior of the purified ß-galactosidase in presence of several bivalent metals. Lowest Km with highest substrate (orthonitrophenyl- ß-galactoside or ONPG) affinity was measured in presence of Ca2+ (42.45 µM ONPG). However, our results demonstrated that Vmax was maximum in presence of Mn+2 (55.98 µM ONP produced mg-1 protein min-1), followed by Fe=2, Zn+2, Mg+2, Cu+2 and Ca+2. A large number of investigations reported Mg+2 as potential co factor for bgalacosidase. However, ß-galactosidase obtained from Arthrobacter oxydans SB has better activity in the presence of Mn+2 or Fe2+.


Assuntos
Arthrobacter/química , Proteínas de Bactérias/química , Coenzimas/química , Magnésio/química , Manganês/química , beta-Galactosidase/química , Arthrobacter/enzimologia , Proteínas de Bactérias/isolamento & purificação , Cálcio/química , Cátions Bivalentes , Cobre/química , Ensaios Enzimáticos , Galactose/química , Glucose/química , Ferro/química , Cinética , Lactose/química , Peso Molecular , Nitrofenilgalactosídeos/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Zinco/química , beta-Galactosidase/isolamento & purificação
7.
Acta Crystallogr F Struct Biol Commun ; 74(Pt 10): 669-676, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30279320

RESUMO

The X-ray structure of ketose 3-epimerase from Arthrobacter globiformis M30, which was previously reported to be a D-allulose 3-epimerase (AgD-AE), was determined at 1.96 Šresolution. The crystal belonged to the hexagonal space group P6522, with unit-cell parameters a = b = 103.98, c = 256.53 Å. The structure was solved by molecular replacement using the structure of Mesorhizobium loti L-ribulose 3-epimerase (MlL-RE), which has 41% sequence identity, as a search model. A hexagonal crystal contained two molecules in the asymmetric unit, and AgD-AE formed a homotetramer with twofold symmetry. The overall structure of AgD-AE was more similar to that of MlL-RE than to the known structures of D-psicose (alternative name D-allulose) 3-epimerases (D-PEs or D-AEs), although AgD-AE and MlL-RE have different substrate specificities. Both AgD-AE and MlL-RE have long helices in the C-terminal region that would contribute to the stability of the homotetramer. AgD-AE showed higher enzymatic activity for L-ribulose than D-allulose; however, AgD-AE is stable and is a unique useful enzyme for the production of D-allulose from D-fructose.


Assuntos
Arthrobacter/química , Proteínas de Bactérias/química , Carboidratos Epimerases/química , Frutose/química , Cetoses/química , Sequência de Aminoácidos , Arthrobacter/enzimologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carboidratos Epimerases/genética , Carboidratos Epimerases/metabolismo , Domínio Catalítico , Clonagem Molecular , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Frutose/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Cetoses/metabolismo , Mesorhizobium/química , Mesorhizobium/enzimologia , Modelos Moleculares , Pentoses/química , Pentoses/metabolismo , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Homologia Estrutural de Proteína , Especificidade por Substrato
8.
Carbohydr Res ; 451: 36-41, 2017 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-28942028

RESUMO

Novel teichulosonic acid with the repeating unit →6)-ß-D-GlcpNAc-(1→8)-α-Kdn-(2→ has been found in the cell walls of two Arthrobacter strains, VKM Ac-2549 and VKM Ac-2550. The teichulosonic acid was revealed in representatives of the genus Arthrobacter for the first time. Two other polymers identified in the above strains were poly(monoglycosyl 1-phosphate) and poly(diglycosyl 1-phosphate) of hitherto unknown structures, i.e., -6)-α-D-GalpNAc-(1-P-, and -6)-ß-D-GlcpNAc-(1→3)-α-D-Galp-(1-P-. The structures of all three polymers were established by using chemical, NMR spectroscopic and ESI-MS methods. The strains studied in this work differ in the cell wall composition from the type strain of phylogenetically closely related species A. crystallopoietes which was reported to contain a teichoic acid and supposedly had a glycosyl 1-phosphate polymer.


Assuntos
Arthrobacter/química , Parede Celular/química , Glucofosfatos/química , Polímeros/química , Ácidos Teicoicos/química , Filogenia
9.
Biochim Biophys Acta Proteins Proteom ; 1865(11 Pt A): 1470-1478, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28843728

RESUMO

The effect of temperature on the reaction of alcohol oxidation catalyzed by choline oxidase was investigated with the S101A variant of choline oxidase. Anaerobic enzyme reduction in a stopped-flow spectrophotometer was biphasic using either choline or 1,2-[2H4]-choline as a substrate. The limiting rate constants klim1 and klim2 at saturating substrate were well separated (klim1/klim2>9), and were >15-fold slower than for wild-type choline oxidase. Solvent deuterium kinetic isotope effects (KIEs) ~4 established that klim1 probes the proton transfer from the substrate hydroxyl to a catalytic base. Primary substrate deuterium KIEs ≥7 demonstrated that klim2 reports on hydride transfer from the choline alkoxide to the flavin. Between 15°C and 39°C the klim1 and klim2 values increased with increasing temperature, allowing for the analyses of H+ and H- transfers using Eyring and Arrhenius formalisms. Temperature-independent KIE on the klim1 value (H2Oklim1/D2Oklim1) suggests that proton transfer occurs within a highly reorganized tunneling-ready-state with a narrow distribution of donor-acceptor distances. Eyring analysis of the klim2 value gave lines with the slope(choline)>slope(D-choline), suggesting kinetic complexity. Spectral evidence for the transient occurrence of a covalent flavin-substrate adduct during the first phase of the anaerobic reaction of S101A CHO with choline is presented, supporting the notion that an important role of amino acid residues in the active site of flavin-dependent enzymes is to eliminate alternative reactions of the versatile enzyme-bound flavin for the reaction that needs to be catalyzed.


Assuntos
Oxirredutases do Álcool/química , Arthrobacter/enzimologia , Proteínas de Bactérias/química , Colina/química , Flavina-Adenina Dinucleotídeo/química , Prótons , Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Substituição de Aminoácidos , Arthrobacter/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biocatálise , Domínio Catalítico , Colina/metabolismo , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Flavina-Adenina Dinucleotídeo/metabolismo , Expressão Gênica , Concentração de Íons de Hidrogênio , Cinética , Mutação , Oxirredução , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Termodinâmica
10.
BMC Biotechnol ; 17(1): 51, 2017 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-28606076

RESUMO

BACKGROUND: The discharge of poorly treated effluents into the environment has far reaching, consequential impacts on human and aquatic life forms. Thus, we evaluated the flocculating efficiency of our test bioflocculant and we report for the first time the ability of the biopolymeric flocculant produced by Arthrobacter humicola in the treatment of sewage wastewater. This strain was isolated from sediment soil sample at Sterkfontein dam in the Eastern Free State province of South Africa. RESULTS: Basic Local Alignment Search Tool (BLAST) analysis of the nucleotide sequence of the 16S rDNA revealed the bacteria to have 99% similarity to Arthrobacter humicola strain R1 and the sequence was deposited in the Gene bank as Arthrobacter humicola with accession number KC816574.1. Flocculating activity was enhanced with the aid of divalent cations, pH 12, at a dosage concentration of 0.8 mg/mL. The purified bioflocculant was heat stable and could retain more than 78% of its flocculating activity after heating at 100 °C for 25 min. Fourier Transform Infrared Spectroscopy analysis demonstrated the presence of hydroxyl and carboxyl moieties as the functional groups. The thermogravimetric analysis was used to monitor the pyrolysis profile of the purified bioflocculant and elemental composition revealed C: O: Na: P: K with 13.90: 41.96: 26.79: 16.61: 0.74 weight percentage respectively. The purified bioflocculant was able to remove chemical oxygen demand, biological oxygen demand, suspended solids, nitrate and turbidity from sewage waste water at efficiencies of 65.7%, 63.5%, 55.7%, 71.4% and 81.3% respectively. CONCLUSIONS: The results of this study indicate the possibility of using the bioflocculant produced by Arthrobacter humicola as a potential alternative to synthesized chemical flocculants in sewage waste water treatment and other industrial waste water.


Assuntos
Arthrobacter/química , Arthrobacter/metabolismo , Esgotos/microbiologia , Microbiologia do Solo , Águas Residuárias/microbiologia , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Arthrobacter/classificação , Arthrobacter/crescimento & desenvolvimento , Biodegradação Ambiental , Floculação , Especificidade da Espécie , Poluentes Químicos da Água/isolamento & purificação
11.
BMC Genomics ; 18(Suppl 2): 104, 2017 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-28361681

RESUMO

BACKGROUND: Computational drug design approaches are important for shortening the time and reducing the cost for drug discovery and development. Among these methods, molecular docking and quantitative structure activity relationship (QSAR) play key roles for lead discovery and optimization. Here, we propose an integrated approach with core strategies to identify the protein-ligand hot spots for QSAR models and lead optimization. These core strategies are: 1) to generate both residue-based and atom-based interactions as the features; 2) to identify compound common and specific skeletons; and 3) to infer consensus features for QSAR models. RESULTS: We evaluated our methods and new strategies on building QSAR models of human acetylcholinesterase (huAChE). The leave-one-out cross validation values q 2 and r 2 of our huAChE QSAR model are 0.82 and 0.78, respectively. The experimental results show that the selected features (resides/atoms) are important for enzymatic functions and stabling the protein structure by forming key interactions (e.g., stack forces and hydrogen bonds) between huAChE and its inhibitors. Finally, we applied our methods to arthrobacter globiformis histamine oxidase (AGHO) which is correlated to heart failure and diabetic. CONCLUSIONS: Based on our AGHO QSAR model, we identified a new substrate verified by bioassay experiments for AGHO. These results show that our methods and new strategies can yield stable and high accuracy QSAR models. We believe that our methods and strategies are useful for discovering new leads and guiding lead optimization in drug discovery.


Assuntos
Acetilcolinesterase/química , Aminoácidos/química , Proteínas de Bactérias/química , Desenho de Drogas , Inibidores Enzimáticos/química , Oxirredutases/química , Arthrobacter/química , Arthrobacter/enzimologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas Ligadas por GPI/antagonistas & inibidores , Proteínas Ligadas por GPI/química , Histamina/química , Humanos , Ligações de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Simulação de Acoplamento Molecular , Oxirredutases/antagonistas & inibidores , Relação Quantitativa Estrutura-Atividade , Eletricidade Estática , Especificidade por Substrato
12.
J Biosci Bioeng ; 123(2): 170-176, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27713017

RESUMO

An enzyme that catalyzes C-3 epimerization between d-fructose and d-allulose was found in Arthrobacter globiformis strain M30. Arthrobacter species have long been used in the food industry and are well-known for their high degree of safety. The enzyme was purified by ion exchange and hydrophobic interaction chromatographies and characterized as a d-allulose 3-epimerase (d-AE). The molecular weight of the purified enzyme was estimated to be 128 kDa with four identical subunits. The enzyme showed maximal activity and thermostability in the presence of Mg2+. The optimal pH and temperature for enzymatic activity were 7.0-8.0 and 70°C, respectively. The enzyme was immobilized to ion exchange resin whereupon it was stable for longer periods than the free enzyme when stored at below 10°C. In the column reaction, the enzyme activity also maintained stability for more than 4 months. Under these conditions, 215 kg of d-allulose produced per liter immobilized enzyme, and this was the highest production yield of d-allulose reported so far. These highly stable properties suggest that this enzyme represents an ideal candidate for the industrial production of d-allulose.


Assuntos
Arthrobacter/enzimologia , Frutose/metabolismo , Racemases e Epimerases/análise , Racemases e Epimerases/isolamento & purificação , Racemases e Epimerases/metabolismo , Arthrobacter/química , Estabilidade Enzimática , Frutose/biossíntese , Concentração de Íons de Hidrogênio , Cinética , Engenharia Metabólica , Peso Molecular , Temperatura Ambiente
13.
Appl Biochem Biotechnol ; 182(1): 216-228, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27878509

RESUMO

A hyaluronate lyase was obtained by cultivating Arthrobacter globiformis strain A152. The enzyme was purified to homogeneity from the supernatant by ammonium sulfate fractionation, Q Sepharose Fast Flow, and Sephadex G-100 chromatography. The purification resulted in a 32.78-fold increase in hyaluronate lyase activity with specific activity of 297.2 U/mg. The molecular weight of the enzyme determined by SDS-PAGE was approximately 73.7 kDa. Using hyaluronic acid (HA) as a substrate, the maximal reaction rate (Vmax) and the Michaelis-Menten constant (Km) of hyaluronate lyase were found to be 4.76 µmol/min/ml and 0.11 mg/ml, respectively. The optimum pH and temperature values for hyaluronate lyase activity were pH 6.0 and 42 °C, respectively. This enzyme was stable at pH 4-10, 5-7, and 5-7 at 4, 37, and 42 °C, respectively. Investigation about temperature effects on hyaluronate lyase displayed that it was stable at 30-37 °C and also showed high activity at 37 °C. The enzymatic activity was enhanced by Ca2+ and was strongly inhibited by Cu2+ and SDS. These properties suggested that the hyaluronate lyase in this study could bring promising prospects in medical and industry applications.


Assuntos
Arthrobacter/química , Proteínas de Bactérias/química , Ácido Hialurônico/química , Polissacarídeo-Liase/química , Arthrobacter/enzimologia , Proteínas de Bactérias/isolamento & purificação , Cálcio/química , Cátions Bivalentes , Cobre/química , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Cinética , Peso Molecular , Polissacarídeo-Liase/isolamento & purificação , Dodecilsulfato de Sódio/química , Especificidade por Substrato , Temperatura Ambiente
14.
J Agric Food Chem ; 64(31): 6188-95, 2016 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-27440442

RESUMO

Inulin fructotransferase (IFTase) is an important enzyme that produces di-d-fructofuranose 1,2':2,3' dianhydride (DAF III), which is beneficial for human health. Present investigations mainly focus on screening and characterizing IFTase, including catalytic efficiency and thermostability, which are two important factors for enzymatic industrial applications. However, few reports aimed to improve these two characteristics based on the structure of IFTase. In this work, a structural model of IFTase (DFA III-producing) from Arthrobacter sp. 161MFSha2.1 was constructed through homology modeling. Analysis of this model reveals that two residues, Ser-309 and Ser-333, may play key roles in the structural stability. Therefore, the functions of the two residues were probed by site-directed mutagenesis combined with the Nano-DSC method and assays for residual activity. In contrast to other mutations, single mutation of serine 309 (or serine 333) to threonine did not decrease the enzymatic stability, whereas double mutation (serine 309 and serine 333 to threonine) can enhance thermostability (by approximately 5 °C). The probable mechanisms for this enhancement were investigated.


Assuntos
Arthrobacter/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Hexosiltransferases/metabolismo , Inulina/metabolismo , Motivos de Aminoácidos , Arthrobacter/química , Arthrobacter/genética , Proteínas de Bactérias/genética , Clonagem Molecular , Estabilidade Enzimática , Hexosiltransferases/química , Hexosiltransferases/genética , Temperatura Alta , Concentração de Íons de Hidrogênio , Mutagênese Sítio-Dirigida , Mutação
15.
Int J Biol Macromol ; 91: 294-8, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27164494

RESUMO

The self-assembly of FtsZ, the bacterial homolog of tubulin, plays an essential role in cell division. Light scattering technique is applied to real-time monitor the in vitro assembly of FtsZ in Arthrobacter strain A3, a newly isolated psychrotrophic bacterium. The critical concentration needed for the assembly is estimated as 6.7µM. The polymerization of FtsZ in Arthrobacter strain A3 requires both GTP and divalent metal ions, while salt is an unfavorable condition for the assembly. The FtsZ polymerizes under a wide range of pHs, with the fastest rate around pH 6.0. The FtsZ from Arthrobacter strain A3 resembles Mycobacterium tuberculosis FtsZ in terms of the dependence on divalent metal ions and the slow polymerization rate, while it is different from M. tuberculosis FtsZ considering the sensitivity to salt and pH. The comparison of FtsZ from different organisms will greatly advance our understanding of the biological role of the key cell division protein.


Assuntos
Arthrobacter/química , Proteínas de Bactérias/química , Proteínas do Citoesqueleto/química , Luz , Espalhamento de Radiação , Mycobacterium tuberculosis/química , Especificidade da Espécie
16.
Mar Drugs ; 14(5)2016 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-27128927

RESUMO

Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 µg/mL) and unreported antimicrobial activity against Bcc strains.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Lipídeos/química , Lipídeos/farmacologia , Regiões Antárticas , Arthrobacter/química , Arthrobacter/genética , Complexo Burkholderia cepacia/química , Complexo Burkholderia cepacia/genética , Genes Bacterianos/genética , Filogenia , Pseudomonas/química , Pseudomonas/genética , Psychrobacter/química , Psychrobacter/genética , RNA Ribossômico 16S/genética
17.
J Hazard Mater ; 304: 118-25, 2016 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-26547620

RESUMO

Vermiculite is one of matrix material used for constructed wetland (CW) for the treatment of municipal wastewater. Arthrobacter sp. strain C21 (CGMCC No. 7671), isolated from a constructed wetland receiving municipal wastewater, forms biofilm on the surface of vermiculite. Di-(2-ethylhexyl) phthalate (DEHP), a typical phthalate pollutant in environment, can be degraded by the biofilm of strain C21 formed on vermiculite. Results of laboratory studies indicated that DEHP was removed from aqueous phase via biodegradation, adsorption by vermiculite, and adsorption by biofilm biomass. Synergistic effect of these three reactions enhanced the overall DEHP removal efficiency. During a batch incubation test with vermiculite and the cell suspension, bacterial adhesion to the media surface occurred within 5h and the phthalate esters (PEs) removal was due to both biodegradation and vermiculite adsorption. As the biofilm developed on surface of vermiculite (5-36 h), biodegradation became the predominance for PEs removal. As mature biofilm was formed (36-54 h), the adsorption of PEs by biofilm biomass became a main driving force for the removal of PEs from aqueous phase. The content of extracellular polymers (EPS) of the biofilm and DEHP removal performance showed a significant positive correlation (rp>0.86).


Assuntos
Silicatos de Alumínio , Arthrobacter/metabolismo , Biofilmes , Dietilexilftalato/metabolismo , Adsorção , Silicatos de Alumínio/química , Arthrobacter/química , Arthrobacter/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento
18.
J Nat Prod ; 78(11): 2827-31, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26575343

RESUMO

Nonfilamentous actinobacteria have been less studied as secondary metabolite producers than their filamentous counterparts such as Streptomyces. From our collection of nonfilamentous actinobacteria isolated from sandstone, an Arthrobacter strain was found to produce a new cyclic peptide arthroamide (1) together with the known compound turnagainolide A (2). These compounds inhibited the quorum sensing signaling of Staphylococcus aureus in the submicromolar to micromolar range.


Assuntos
Arthrobacter/química , Depsipeptídeos/isolamento & purificação , Depsipeptídeos/química , Depsipeptídeos/farmacologia , Estrutura Molecular , Percepção de Quorum , Staphylococcus aureus
19.
Mikrobiologiia ; 84(3): 291-310, 2015.
Artigo em Russo | MEDLINE | ID: mdl-26263689

RESUMO

Efficiency of MALDI mass spectrometry for differentiation between phenotypic phase variants (in colony morphology and virulence/avirulence) was investigated.for saprotrophic and opportunistically pathogenic bacteria of five genera (Acinetobacter, Arthrobacter, Rhodococcus, Corynebacterium, and Escherichia). Analysis of MALDI spectra (on the SA and HCCA matrices) included: (1) determination of similarity of the protein spectra as a percentage of the common protein peaks to the total amount of proteins, which reflects the phylogenetic relationships of the objects and has been recommended for identification of closely related species; (2) comparison of intensities of the common peaks; and (3) the presence of specific peaks as determinative characteristics of the variants. Under the standard analytical conditions the similarity between the MALDI profiles was shown to increase in the row: genus-species-strain-variant. Assessment of intensities of the common peaks was most applicable for differentiation between phase variants, especially in the case of high similarity of their profiles. Phase variants (A. oxydans strain K14) with similar colony morphotypes (S, R, M, and S(m)) grown on different media (LB agar, TSA, and TGYg) exhibited differences in their protein profiles reflecting the differences in their physiological characteristics. This finding is in agreement with our previous results on screening of the R. opacus with similar colony morphology and different substrate specificity in decomposition of chlorinated phenols. Analysis of MALDI spectra is probably the only efficient method for detection of such variants.


Assuntos
Acinetobacter/classificação , Arthrobacter/classificação , Proteínas de Bactérias/isolamento & purificação , Corynebacterium/classificação , Escherichia/classificação , Rhodococcus/classificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/estatística & dados numéricos , Acinetobacter/química , Acinetobacter/metabolismo , Acinetobacter/patogenicidade , Arthrobacter/química , Arthrobacter/metabolismo , Arthrobacter/patogenicidade , Proteínas de Bactérias/classificação , Técnicas de Tipagem Bacteriana/instrumentação , Corynebacterium/química , Corynebacterium/metabolismo , Corynebacterium/patogenicidade , Interpretação Estatística de Dados , Escherichia/química , Escherichia/metabolismo , Escherichia/patogenicidade , Fenótipo , Filogenia , Rhodococcus/química , Rhodococcus/metabolismo , Rhodococcus/patogenicidade , Virulência
20.
Int J Biol Macromol ; 81: 235-40, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26187190

RESUMO

The exopolysaccharides from Arthrobacter sp. B4 (B4-EPS) exhibited an excellent chromium (VI) (Cr(VI)) removal capability without any pH adjustment, whereby 50mgL(-1) of Cr(VI) could be completely removed by 4gL(-1) of B4-EPS. The kinetics tests revealed that the first-order rate constant was 8.3×10(-5)s(-1) and the optimal reaction time was 720min. However, a low initial concentration of Cr(VI) (5-30mgL(-1)) would accelerate the reaction rate of Cr(VI) removal and shorten reaction time to less than 360min. Meanwhile, the X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-vis) spectra indicated that Cr(VI) was reduced to Cr(III) by B4-EPS in accordance with the emergence of the green reaction products. Furthermore, the Fourier transform-infrared spectra (FT-IR) and nuclear magnetic resonance (NMR) showed that carboxyl and hydroxyl groups of B4-EPS contributed to Cr(VI) reduction. Additionally, a feasible scheme for Cr(VI) detoxification by oxidation and flocculation of B4-EPS is presented.


Assuntos
Arthrobacter/química , Arthrobacter/metabolismo , Cromo/metabolismo , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/metabolismo , Floculação , Concentração de Íons de Hidrogênio , Inativação Metabólica , Cinética , Espectroscopia de Ressonância Magnética , Oxirredução , Espectroscopia de Infravermelho com Transformada de Fourier
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