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1.
Adv Exp Med Biol ; 1141: 101-202, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571165

RESUMO

Solute carrier (SLC) family transporters utilize an electrochemical potential difference or an ion gradient generated by primary active transporters for transporting their substrates across biological membranes. These transporters are categorized as facilitated transporters or secondary active transporters. More than 300 SLC transporters have been identified. SLC transporters related to drug transport mainly include SLC21 gene subfamily (organic anion-transporting polypeptides, OATPs), SLC22A gene subfamily (organic anion transporters, OATs; organic cation transporters, OCTs; or organic cation/carnitine transporters, OCTNs), SLC15A gene subfamily (peptide transporters, PEPTs), and SLC47A gene subfamily (multidrug and toxin extrusion, MATEs). In general, OCTs transport organic cations, OATPs transport large and fairly hydrophobic organic anions, OATs transport the smaller and more hydrophilic organic anions, and PEPTs are responsible for the uptake of di-/tripeptides and peptide-like drugs. MATEs are responsible for efflux of organic cations. These transporters also transport some endogenous substances, indicating that the dysfunction of SLCs not only disrupts homeostasis but also largely impacts on the disposition of their substrate drugs. This chapter will discuss these SLC family transporters, with an emphasis on tissue distribution, substrate specificity, transporter physiology, and clinical significance.


Assuntos
Proteínas Carreadoras de Solutos , Animais , Cátions/metabolismo , Humanos , Peptídeos/metabolismo , Preparações Farmacêuticas/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Especificidade por Substrato , Distribuição Tecidual/fisiologia
2.
J Agric Food Chem ; 67(38): 10744-10755, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31525900

RESUMO

We previously reported that ß-glucosidase BGL1 at low concentration (15 µg mL-1) from Coprinopsis cinerea exhibited hydrolytic activity only toward laminarioligosaccharides but not toward cellooligosaccharides and gentiobiose. This study shows that BGL1 at high concentration (200 µg mL-1) also hydrolyzed cellobiose and gentiobiose, which accounted for only 0.83 and 2.05% of its activity toward laminaribiose, respectively. Interestingly, BGL1 at low concentration (1.5 µg mL-1) showed transglycosylation but BGL1 at high concentration (200 µg mL-1) did not. BGL1 utilizes only laminarioligosaccharides but not glucose, gentiobiose, and cellobiose to synthesize the higher oligosaccharides. BGL1 transferred one glucosyl residue from substrate laminarioligosaccharide to another laminarioligosaccharide as an acceptor in a ß(1 → 3) or ß(1 → 6) fashion to produce higher laminarioligosaccharides or 3-O-ß-d-gentiobiosyl-d-laminarioligosaccharides. The BGL1-digested laminaritriose exhibited approximately 90% enhancement in the anti-oxidant activity compared to that of untreated laminaritriose, implying a potential application of BGL1-based transglycosylation for the production of high value-added rare oligosaccharides.


Assuntos
Agaricales/enzimologia , Dissacarídeos/metabolismo , Proteínas Fúngicas/química , Oligossacarídeos/metabolismo , beta-Glucosidase/química , Agaricales/química , Agaricales/genética , Sequência de Aminoácidos , Dissacarídeos/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glicosilação , Hidrólise , Cinética , Estrutura Molecular , Oligossacarídeos/química , Especificidade por Substrato , beta-Glucosidase/genética , beta-Glucosidase/metabolismo
3.
Toxicol Lett ; 314: 181-186, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31404594

RESUMO

The cytochrome P450 enzyme (CYP) family includes key enzymes for the metabolism of drugs and xenobiotics. Several animal models have been used to determine the metabolite profile of specific drugs. Among these are porcine microsomes prepared from Göttingen minipigs. However, CYP expression profile in microsomes from this pig breed is unknown. In the present study, we determined the mRNA and protein profiles of a comprehensive selection of CYPs in microsomes prepared from male and female Göttingen minipigs. Using RT-PCR, western blotting and mass spectroscopy, we found that the expression levels of CYP1A, CYP2A and CYP2E1 were significantly higher in females than males. Moreover, some of the transcription factors controlling CYP transcription also showed a sex-dependent expression pattern. Conversely, expression of CYP2B, CYP2D and CYP3A was comparable between sexes. The overall CYP expression distribution showed high similarity with what previously been reported in humans. In conclusion, our results suggest that Göttingen minipigs are a reliable model for studying CYPs.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Fígado/enzimologia , Animais , Sistema Enzimático do Citocromo P-450/genética , Feminino , Regulação Enzimológica da Expressão Gênica , Isoenzimas , Masculino , Microssomos/enzimologia , Modelos Animais , Fatores Sexuais , Especificidade por Substrato , Suínos , Porco Miniatura
4.
Bioresour Technol ; 291: 121863, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31376664

RESUMO

This study examined the influence of the application of brewery spent grain (BSG) on biogas production efficiency as well as its kinetics in the co-digestion of acid cheese whey (ACW) and sewage sludge (SS). The experiment was conducted in semi-flow anaerobic reactors under mesophilic conditions (35 °C) with different hydraulic retention times (HRT) of 16.7 d, 18 d and 20 d. The results indicate that the addition of BSG significantly enhanced the biogas yields, ensuring good process stability. The highest value of 0.54 m3 kg-1 VSadded was obtained at HRT of 16.7 d, while for ACW and SS it was only 0.50 m3 kg-1 VSadded at HRT 18 d. However, the decrease in the rate constant k occurred (0.07 h-1) as compared to the two-component system (0.096 h-1). The highest energy profit of 160% was enhanced for the three-substrate co-digestion, indicating it as a cost-effective solution.


Assuntos
Queijo , Grão Comestível/metabolismo , Esgotos , Soro do Leite/metabolismo , Anaerobiose , Biocombustíveis/análise , Grão Comestível/química , Especificidade por Substrato
5.
J Agric Food Chem ; 67(37): 10373-10379, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31453692

RESUMO

Agarose can be hydrolyzed into agarooligosaccharides (AOSs) by α-agarase, which is an important enzyme for efficient saccharification of agarose or preparation of bioactive oligosaccharides from agarose. Although many ß-agarases have been reported and characterized, there are only a few studies on α-agarases. Here, we cloned a novel α-agarase named CaLJ96 with a molecular weight of approximately 200 kDa belonging to glycoside hydrolase family 96 from Catenovulum agarivorans. CaLJ96 has good pH stability and exhibits maximum activity at 37 °C and pH 7.0. The hydrolyzed products of agarose by CaLJ96 are analyzed as agarobiose (A2), agarotetraose (A4), and agarohexaose (A6), in which A4 is the dominant product. CaLJ96 can hydrolyze agaropentaose (A5) into A2 and agarotriose (A3) and A6 into A2 and A4 but cannot act on A2, A3, or A4. This is the first report to characterize the α-agarase action on AOSs in detail. Therefore, CaLJ96 has potential for the manufacture of bioactive AOSs.


Assuntos
Alteromonadaceae/enzimologia , Proteínas de Bactérias/química , Glicosídeo Hidrolases/química , Alteromonadaceae/química , Alteromonadaceae/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clonagem Molecular , Estabilidade Enzimática , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Temperatura Alta , Concentração de Íons de Hidrogênio , Peso Molecular , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Sefarose/química , Sefarose/metabolismo , Especificidade por Substrato
6.
J Enzyme Inhib Med Chem ; 34(1): 1474-1480, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31414611

RESUMO

The discovery of allosteric modulators is a multi-disciplinary approach, which is time- and cost-intensive. High-throughput screening combined with novel computational tools can reduce these factors. Thus, we developed an enzyme activity assay, which can be included in the drug discovery work-flow subsequent to the in-silico library screening. While the in-silico screening yields in the identification of potential allosteric modulators, the developed in-vitro assay allows for the characterisation of them. Candida rugosa lipase (CRL), a glyceride hydrolysing enzyme, has been selected for the pilot development. The assay conditions were adjusted to CRL's properties including pH, temperature and substrate specificity for two different substrates. The optimised assay conditions were validated and were used to characterise Tropolone, which was identified as an allosteric modulator. In conclusion, the assay is a reliable, reproducible, and robust tool, which can be streamlined with in-silico screening and incorporated in an automated high-throughput screening workflow.


Assuntos
Lipase/metabolismo , Miniaturização , Regulação Alostérica , Candida/enzimologia , Cristalografia por Raios X , Estabilidade Enzimática , Ensaios de Triagem em Larga Escala , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Cinética , Limite de Detecção , Lipase/química , Reprodutibilidade dos Testes , Especificidade por Substrato , Temperatura Ambiente
7.
Exp Parasitol ; 205: 107748, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31442453

RESUMO

Trypanosoma cruzi (the causative agent of Chagas disease) presents a complex life cycle that involves adaptations in vertebrate and invertebrate hosts. As a protozoan parasite of hematophagous insects and mammalian hosts, T. cruzi is exposed to reactive oxygen species (ROS). To investigate the functionality of T. cruzi tartrate-resistant acid phosphatase type 5 (TcACP5), we cloned, superexpressed and purified the enzyme. Purified TcACP5 exhibited a Vmax and apparent Km for pNPP hydrolysis of 7.7 ±â€¯0.2 nmol pNP × µg-1 × h-1 and 169.3 ±â€¯22.6 µM, respectively. The pH dependence was characterized by sharp maximal activity at pH 5.0, and inhibition assays demonstrated its sensitivity to acid phosphatase inhibitors. Similar activities were obtained with saturating concentrations of P-Ser and P-Thr as substrates. The enzyme metabolizes hydrogen peroxide (H2O2) in vitro, and parasites superexpressing this enzyme were more resistant to oxidative stress promoted by H2O2. Taken together, these results suggest that TcACP5 plays a central role in phosphoryl transfer and redox reactions.


Assuntos
Peróxido de Hidrogênio/farmacologia , Estresse Oxidativo/fisiologia , Fosfatase Ácida Resistente a Tartarato/metabolismo , Trypanosoma cruzi/enzimologia , Sequência de Aminoácidos , Imunofluorescência , Regulação Enzimológica da Expressão Gênica , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Microscopia Confocal , Oxirredução , Especificidade por Substrato , Fosfatase Ácida Resistente a Tartarato/antagonistas & inibidores , Fosfatase Ácida Resistente a Tartarato/química , Transfecção , Trypanosoma cruzi/efeitos dos fármacos
8.
J Agric Food Chem ; 67(31): 8573-8580, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31293156

RESUMO

Glycosylation endows both natural and synthetic small molecules with modulated physicochemical and biological properties. Plant and bacterial glycosyltransferases capable of decorating various privileged scaffolds have been extensively studied, but those from kingdom Fungi still remain underexploited. Here, we use a combination of genome mining and heterologous expression techniques to identify four novel glycosyltransferase-methyltransferase (GT-MT) functional modules from Hypocreales fungi. These GT-MT modules display decent substrate promiscuity and regiospecificity, methylglucosylating a panel of natural products such as flavonoids, stilbenoids, anthraquinones, and benzenediol lactones. Native GT-MT modules can be split up and regrouped into hybrid modules with similar or even improved efficacy as compared with native pairs. Methylglucosylation of kaempferol considerably improves its insecticidal activity against the larvae of oriental armyworm Mythimna separata (Walker). Our work provides a set of efficient biocatalysts for the combinatorial biosynthesis of small molecule glycosides that may have significant importance to the pharmaceutical, agricultural, and food industries.


Assuntos
Proteínas Fúngicas/química , Glicosiltransferases/química , Hypocreales/enzimologia , Metiltransferases/química , Fenóis/química , Animais , Biocatálise , Cristalografia por Raios X , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glicosilação , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Hypocreales/genética , Inseticidas/química , Inseticidas/farmacologia , Metilação , Metiltransferases/genética , Metiltransferases/metabolismo , Mariposas/efeitos dos fármacos , Fenóis/farmacologia , Especificidade por Substrato
9.
J Microbiol Biotechnol ; 29(7): 1043-1052, 2019 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-31353877

RESUMO

Active lipase-producing bacterium Burkholderia gladioli Bps-1 was rapidly isolated using a modified trypan blue and tetracycline, ampicillin (TB-TA) plate. The electro-phoretically pure enzyme was obtained by purification using ethanol precipitation, ion-exchange chromatography, and gel filtration chromatography. The molecular weight was 34.6 kDa and the specific activity was determined to be 443.9 U/mg. The purified lipase showed the highest activity after hydrolysis with p-NPC16 at a pH of 8.5 and 50°C, and the Km, kcat, and kcat/Km values were 1.05, 292.95 s-1 and 279 s-1mM-1, respectively. The lipase was highly stable at 7.5 ≤ pH ≤ 10.0. K+ and Na+ exerted activation effects on the lipase which had favorable tolerance to short-chain alcohols with its residual enzyme activity being 110% after being maintained in 30% ethanol for 1 h. The results demonstrated that the lipase produced by the strain B. gladioli Bps-1 has high enzyme activity and is an alkaline lipase. The lipase has promising chemical properties for a range of applications in the food-processing and detergent industries, and has particularly high potential for use in the manufacture of biodiesel.


Assuntos
Burkholderia gladioli/enzimologia , Burkholderia gladioli/isolamento & purificação , Lipase/metabolismo , Biocatálise , Biocombustíveis , Burkholderia gladioli/crescimento & desenvolvimento , Burkholderia gladioli/metabolismo , Meios de Cultura , Detergentes , Estabilidade Enzimática , Etanol/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Lipase/química , Lipase/isolamento & purificação , Peso Molecular , Especificidade por Substrato , Temperatura Ambiente
10.
Chem Commun (Camb) ; 55(58): 8390-8393, 2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31257394

RESUMO

Diverse bioactive alkaloids with a tryptophan 2,5-diketopiperazine (DKP) core and an annulated structure forming a methylated pyrroloindoline-DKP assembly have been isolated from various microbial sources. However, little is known about their biosynthesis. In this study, a novel indole C3 methyltransferase from Streptomyces sp. HPH0547 was discovered and characterized. Structural elucidation of the products revealed that this enzyme catalyzed unique pyrroloindoline cyclization in tryptophan-containing cyclodipeptides. This is the first C3 methyltransferase reported to catalyze pyrroloindoline cyclization in cyclic dipeptides, which provides a feasible and simple method to access diverse alkaloids.


Assuntos
Alcaloides/biossíntese , Proteínas de Bactérias/metabolismo , Dipeptídeos/biossíntese , Metiltransferases/metabolismo , Peptídeos Cíclicos/biossíntese , Streptomyces/enzimologia , Ciclização , Dicetopiperazinas/metabolismo , Modelos Químicos , Especificidade por Substrato , Triptofano/química , Triptofano/metabolismo
11.
Sheng Wu Gong Cheng Xue Bao ; 35(7): 1234-1246, 2019 Jul 25.
Artigo em Chinês | MEDLINE | ID: mdl-31328480

RESUMO

1,3-1,4-ß-glucanase (E.C.3.2.1.73) is an important industrial enzyme which cleave ß-glucans into oligosaccharides through strictly cutting the ß-1,4 glycosidic bonds in 3-O-substituted glucopyranose units. Microbial 1,3-1,4-ß-glucanase belongs to retaining glycosyl hydrolases of family 16 with a jellyroll ß-sandwich fold structure. The present paper reviews the industrial application and protein engineering of microbial ß-glucanases in the last decades and forecasts the research prospects of microbial ß-glucanases.


Assuntos
Engenharia de Proteínas , Sequência de Aminoácidos , Glicosídeo Hidrolases , Modelos Moleculares , Especificidade por Substrato
12.
J Agric Food Chem ; 67(29): 8177-8185, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31290662

RESUMO

Trehalose synthase (TreS) catalyzes the reversible interconversion of maltose to trehalose, and is therefore essential for trehalose production. Consequently, dissecting the catalytic mechanism of TreS is important for enzyme optimization and industrial applications. TreS from Thermobaculum terrenum (TtTreS) is a thermostable enzyme. Here, we studied the composition of the TtTreS active site through computer calculation and enzyme analysis. The results were consistent with a two-step double-displacement mechanism, similar to that of glycoside hydrolase 13 family enzymes. However, our data suggested that glucose rotation, following breakage of the α-1,4 glycosidic bond, is a key factor determining the reaction direction and conversion rate. The N246 residue plays an important role in glucose rotation. Moreover, we established a saturated mutation model for the nonconserved amino acids around the substrate gateway domain. Finally, four TtTreS mutants (K136T, Y137D, K138N, and D139S) resulted in improved trehalose yield compared to that of the wild-type enzyme.


Assuntos
Bactérias/enzimologia , Proteínas de Bactérias/química , Glucosiltransferases/química , Bactérias/química , Bactérias/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Catálise , Domínio Catalítico , Biologia Computacional , Estabilidade Enzimática , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Temperatura Alta , Especificidade por Substrato
13.
Food Chem ; 298: 125004, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260986

RESUMO

There is general interest in strategies to control polyphenol oxidase (PPO)-initiated enzymatic browning because it is often associated with declining food quality. Cyclodextrins are cyclic glucan oligosaccharides that form inclusion complexes with a number of PPO substrates. This study focuses on the effect of ß-cyclodextrins (ßCyD) on PPO-catalyzed reactions. Potato enzyme extracts and semi-purified potato PPO served as enzyme sources. Substrates included phenolics endogenous to potatoes. Reaction time-courses were followed spectrophotometrically; rates were compared by analysis of variance. Extents of ßCyD inhibition of PPO-catalyzed reactions are shown to be substrate specific and can be quantitatively accounted for based on degrees of ßCyD substrate sequestration. There was no evidence for direct irreversible ßCyD inactivation of potato PPO. An apparent "direct PPO inactivation" by ßCyD is shown to result from a sequence of sequestration-dependent reactions that occur in commonly employed assay systems for the quantification of PPO in fruits and vegetables.


Assuntos
Catecol Oxidase/química , Catecol Oxidase/metabolismo , Solanum tuberosum/enzimologia , beta-Ciclodextrinas/química , Catálise , Catecol Oxidase/antagonistas & inibidores , Fenóis/química , Fenóis/metabolismo , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Especificidade por Substrato , beta-Ciclodextrinas/metabolismo
14.
Food Chem ; 298: 124999, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31261010

RESUMO

Glycoside hydrolase family 8 (GH8) includes endoglucanases, lichenases, chitosanases and xylanases, which are essential for polysaccharides breakdown. In this work, we studied a thermally stable GH8 from the cellulose synthase complex of Enterobacter sp. R1, for deconstruction of ß-glucans. The biochemical characterization of the recombinant GH8ErCel showed high specificity towards barley ß-glucan and lichenan and lower activity on carboxymethylcellulose and swollen cellulose, yielding different length oligosaccharides. By molecular modeling, six conserved subsites for glucose binding and some possible determinants for its lack of xylanase and chitosanase activity were identified. GH8ErCel was active at a broad range of pH and temperature and presented remarkable stability at 60 °C. Additionally, it hydrolyzed ß-glucan from oat and wheat brans mainly to tri- and tetraoligosaccharides. Therefore, GH8ErCel may be a good candidate for enzymatic deconstruction of ß-glucans at high temperature in food and feed industries, including the production of prebiotics and functional foods.


Assuntos
Celulase/química , Celulase/metabolismo , Celulose/metabolismo , Enterobacter/enzimologia , beta-Glucanas/metabolismo , Argentina , Carboximetilcelulose Sódica/metabolismo , Celulase/genética , Enterobacter/genética , Enterobacter/isolamento & purificação , Estabilidade Enzimática , Glucanos/metabolismo , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Oligossacarídeos/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Microbiologia do Solo , Especificidade por Substrato , Temperatura Ambiente , beta-Glucanas/química
15.
Ecotoxicol Environ Saf ; 182: 109416, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31301596

RESUMO

The main objectives of this study were to purify the glutathione S-transfereses (GSTs) and assess the effect of high doses of acrylamide (ACR) on male albino Wistar rat liver, kidney, testis and bran GST activities, and expression analysis of GST. ACR (50 mg/300 ml) was ingested for 40 days (20 doses) in drinking water on alternative days, on 40 day post ingestion the control and treated tissues were collected for GST purification by affinity column and biochemical characterization of GSTs by substrate specificities, and GST expression by immuno dot blots. In the analysis of the purified GSTs, we observed that liver GSTs were resolved in to three bands known as Yc, Yb and Ya; kidney GSTs were resolved in to two bands known as Yc and Ya; testis and brain GSTs were resolved as four bands known as Yc, Yb, Yß and Yδ on 12.5% sodium dodecyl sulfate polyacrylamide gel (SDS PAGE). In the analysis of biochemical characterization, we observed a significant decrease (p < 0.05) in the specific activities of liver GST isoforms with the substrates 1-chloro 2,4-dinitrobenzene (CDNB), bromosulfophthalein (BSP), p-nitrophenyl acetate (pNPA), p-nitrobenzyl chloride (pNBC) and cumene hydroperoxide (CHP), but showed no activity with ethacrynic acid (ECA) and significant decrease (p < 0.05) in the specific activities of kidney GST isoforms with the substrates CDNB, pNPA, pNBC and CHP, but showed no activity with BSP and ECA, and a significant decrease (p < 0.05) in the specific activities of testis and brain GST isoforms with the substrates CDNB, BSP, pNPA, pNBC, ECA and CHP. In the analysis of immuno dot blots, we observed a decreased expression of liver, kidney, testis and brain GSTs. Through the affinity purification and biochemical characterization, we observed a tissue specific distribution of GSTs that is liver GSTs possess Yc, Yb and Ya sub units known as alpha (α) and mu (µ) class GSTs; kidney GSTs possess Yc and Ya sub units known as (α) alpha class GST; testis and brain GSTs possess Yc, Yb, Yß and Yδ sub units known as alpha (α), mu (µ) and pi (π) class GSTs. Purification studies, biochemical characterization and immuno dot blot analysis were revealed the GSTs were sensitive to high doses of ACR and the high level exposure to ACR cause the damage of detoxification function of GST due to decreased expression and hence lead to cellular dysfunction of vital organs.


Assuntos
Acrilamida/toxicidade , Glutationa Transferase/metabolismo , Animais , Eletroforese em Gel de Poliacrilamida , Glutationa/metabolismo , Isoenzimas , Rim/metabolismo , Fígado/metabolismo , Masculino , Nitrobenzenos , Nitrofenóis , Ratos , Ratos Wistar , Especificidade por Substrato , Testículo/metabolismo , Distribuição Tecidual
16.
Acta Crystallogr D Struct Biol ; 75(Pt 6): 578-591, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31205020

RESUMO

Coagulation factor XII (FXII) is a key initiator of the contact pathway, which contributes to inflammatory pathways. FXII circulates as a zymogen, which when auto-activated forms factor XIIa (FXIIa). Here, the production of the recombinant FXIIa protease domain (ßFXIIaHis) with yields of ∼1-2 mg per litre of insect-cell culture is reported. A second construct utilized an N-terminal maltose-binding protein (MBP) fusion (MBP-ßFXIIaHis). Crystal structures were determined of MBP-ßFXIIaHis in complex with the inhibitor D-Phe-Pro-Arg chloromethyl ketone (PPACK) and of ßFXIIaHis in isolation. The ßFXIIaHis structure revealed that the S2 and S1 pockets were occupied by Thr and Arg residues, respectively, from an adjacent molecule in the crystal. The Thr-Arg sequence mimics the P2-P1 FXIIa cleavage-site residues present in the natural substrates prekallikrein and FXII, and Pro-Arg (from PPACK) mimics the factor XI cleavage site. A comparison of the ßFXIIaHis structure with the available crystal structure of the zymogen-like FXII protease revealed large conformational changes centred around the S1 pocket and an alternate conformation for the 99-loop, Tyr99 and the S2 pocket. Further comparison with activated protease structures of factors IXa and Xa, which also have the Tyr99 residue, reveals that a more open form of the S2 pocket only occurs in the presence of a substrate mimetic. The FXIIa inhibitors EcTI and infestin-4 have Pro-Arg and Phe-Arg P2-P1 sequences, respectively, and the interactions that these inhibitors make with ßFXIIa are also described. These structural studies of ßFXIIa provide insight into substrate and inhibitor recognition and establish a scaffold for the structure-guided drug design of novel antithrombotic and anti-inflammatory agents.


Assuntos
Fator XIIa , Proteínas Ligantes de Maltose , Proteínas Recombinantes de Fusão/química , Clorometilcetonas de Aminoácidos/química , Animais , Sítios de Ligação , Linhagem Celular , Cristalização , Cristalografia por Raios X/métodos , Drosophila melanogaster , Fator XIIa/química , Fator XIIa/metabolismo , Proteínas Ligantes de Maltose/química , Proteínas Ligantes de Maltose/metabolismo , Modelos Moleculares , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Especificidade por Substrato
17.
Acta Crystallogr D Struct Biol ; 75(Pt 6): 605-615, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31205022

RESUMO

The discovery of new glycoside hydrolases that can be utilized in the chemoenzymatic synthesis of carbohydrates has emerged as a promising approach for various biotechnological processes. In this study, recombinant Ps_Cel5A from Pseudomonas stutzeri A1501, a novel member of the GH5_5 subfamily, was expressed, purified and crystallized. Preliminary experiments confirmed the ability of Ps_Cel5A to catalyze transglycosylation with cellotriose as a substrate. The crystal structure revealed several structural determinants in and around the positive subsites, providing a molecular basis for a better understanding of the mechanisms that promote and favour synthesis rather than hydrolysis. In the positive subsites, two nonconserved positively charged residues (Arg178 and Lys216) were found to interact with cellobiose. This adaptation has also been reported for transglycosylating ß-mannanases of the GH5_7 subfamily.


Assuntos
Proteínas de Bactérias/química , Celulase/química , Celulose/química , Pseudomonas stutzeri/enzimologia , Trioses/química , Celulose/metabolismo , Cristalização , Cristalografia por Raios X/métodos , Escherichia coli , Glicosilação , Especificidade por Substrato , Trioses/metabolismo
18.
Nature ; 571(7764): 275-278, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31181567

RESUMO

Recently developed DNA base editing methods enable the direct generation of desired point mutations in genomic DNA without generating any double-strand breaks1-3, but the issue of off-target edits has limited the application of these methods. Although several previous studies have evaluated off-target mutations in genomic DNA4-8, it is now clear that the deaminases that are integral to commonly used DNA base editors often bind to RNA9-13. For example, the cytosine deaminase APOBEC1-which is used in cytosine base editors (CBEs)-targets both DNA and RNA12, and the adenine deaminase TadA-which is used in adenine base editors (ABEs)-induces site-specific inosine formation on RNA9,11. However, any potential RNA mutations caused by DNA base editors have not been evaluated. Adeno-associated viruses are the most common delivery system for gene therapies that involve DNA editing; these viruses can sustain long-term gene expression in vivo, so the extent of potential RNA mutations induced by DNA base editors is of great concern14-16. Here we quantitatively evaluated RNA single nucleotide variations (SNVs) that were induced by CBEs or ABEs. Both the cytosine base editor BE3 and the adenine base editor ABE7.10 generated tens of thousands of off-target RNA SNVs. Subsequently, by engineering deaminases, we found that three CBE variants and one ABE variant showed a reduction in off-target RNA SNVs to the baseline while maintaining efficient DNA on-target activity. This study reveals a previously overlooked aspect of off-target effects in DNA editing and also demonstrates that such effects can be eliminated by engineering deaminases.


Assuntos
DNA/genética , Edição de Genes/métodos , Mutagênese , Mutação , Nucleosídeo Desaminases/genética , Engenharia de Proteínas , RNA/genética , Adenina/metabolismo , Aminoidrolases/genética , Aminoidrolases/metabolismo , Citosina/metabolismo , Citosina Desaminase/genética , Citosina Desaminase/metabolismo , Células HEK293 , Humanos , Nucleosídeo Desaminases/metabolismo , Especificidade por Substrato , Transfecção
19.
Nature ; 571(7764): 219-225, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31189177

RESUMO

Conventional CRISPR-Cas systems maintain genomic integrity by leveraging guide RNAs for the nuclease-dependent degradation of mobile genetic elements, including plasmids and viruses. Here we describe a notable inversion of this paradigm, in which bacterial Tn7-like transposons have co-opted nuclease-deficient CRISPR-Cas systems to catalyse RNA-guided integration of mobile genetic elements into the genome. Programmable transposition of Vibrio cholerae Tn6677 in Escherichia coli requires CRISPR- and transposon-associated molecular machineries, including a co-complex between the DNA-targeting complex Cascade and the transposition protein TniQ. Integration of donor DNA occurs in one of two possible orientations at a fixed distance downstream of target DNA sequences, and can accommodate variable length genetic payloads. Deep-sequencing experiments reveal highly specific, genome-wide DNA insertion across dozens of unique target sites. This discovery of a fully programmable, RNA-guided integrase lays the foundation for genomic manipulations that obviate the requirements for double-strand breaks and homology-directed repair.


Assuntos
Sistemas CRISPR-Cas/genética , Elementos de DNA Transponíveis/genética , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Edição de Genes/métodos , Mutagênese Insercional/métodos , RNA Bacteriano/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Proteínas Associadas a CRISPR/genética , Proteínas Associadas a CRISPR/metabolismo , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/metabolismo , Escherichia coli/genética , Genoma Bacteriano/genética , Integrases/genética , Integrases/metabolismo , Mutagênese Sítio-Dirigida/métodos , RNA Guia/genética , Especificidade por Substrato , Vibrio cholerae/genética
20.
Nat Commun ; 10(1): 2534, 2019 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-31182716

RESUMO

The suppressor of cytokine signaling 2 (SOCS2) acts as substrate recognition subunit of a Cullin5 E3 ubiquitin ligase complex. SOCS2 binds to phosphotyrosine-modified epitopes as degrons for ubiquitination and proteasomal degradation, yet the molecular basis of substrate recognition has remained elusive. Here, we report co-crystal structures of SOCS2-ElonginB-ElonginC in complex with phosphorylated peptides from substrates growth hormone receptor (GHR-pY595) and erythropoietin receptor (EpoR-pY426) at 1.98 Å and 2.69 Å, respectively. Both peptides bind in an extended conformation recapitulating the canonical SH2 domain-pY pose, but capture different conformations of the EF loop via specific hydrophobic interactions. The flexible BG loop is fully defined in the electron density, and does not contact the substrate degron directly. Cancer-associated SNPs located around the pY pocket weaken substrate-binding affinity in biophysical assays. Our findings reveal insights into substrate recognition and specificity by SOCS2, and provide a blueprint for small molecule ligand design.


Assuntos
Proteínas Supressoras da Sinalização de Citocina/química , Ubiquitina-Proteína Ligases/química , Cristalografia por Raios X , Humanos , Fosfotirosina/química , Polimorfismo de Nucleotídeo Único , Conformação Proteica , Receptores da Eritropoetina/química , Receptores da Somatotropina/química , Alinhamento de Sequência , Especificidade por Substrato , Proteínas Supressoras da Sinalização de Citocina/genética , Ubiquitinação
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