DNA methylases for site-selective inhibition of type IIS restriction enzyme activity.

DNA methylases of the restriction-modifications (R-M) systems are promising enzymes for the development of novel molecular and synthetic biology tools. Their use in vitro enables the deployment of independent and controlled catalytic reactions. This work aimed to produce recombinant DNA methylases belonging to the R-M systems, capable of in vitro inhibition of the type IIS restriction enzymes BsaI, BpiI, or LguI. Non-switchable methylases are those whose recognition sequences fully overlap the recognition sequences of their associated endonuclease. In switch methylases, the methylase and endonuclease recognition sequences only partially overlap, allowing sequence engineering to alter methylation without altering restriction. In this work, ten methylases from type I and II R-M systems were selected for cloning and expression in E. coli strains tolerant to methylation. Isopropyl ß-D-1-thiogalactopyranoside (IPTG) concentrations and post-induction temperatures were tested to optimize the soluble methylases expression, which was achieved with 0.5 mM IPTG at 20 °C. The C-terminal His6-Tag versions showed better expression than the N-terminal tagged versions. DNA methylation was analyzed using purified methylases and custom test plasmids which, after the methylation reactions, were digested using the corresponding associated type IIS endonuclease. The non-switchable methylases M2.Eco31I, M2.BsaI, M2.HpyAII, and M1.MboII along with the switch methylases M.Osp807II and M2.NmeMC58II showed the best activity for site-selective inhibition of type IIS restriction enzyme activity. This work demonstrates that our recombinant methylases were able to block the activity of type IIS endonucleases in vitro, allowing them to be developed as valuable tools in synthetic biology and DNA assembly techniques. KEY POINTS: • Non-switchable methylases always inhibit the relevant type IIS endonuclease activity • Switch methylases inhibit the relevant type IIS endonuclease activity depending on the sequence engineering of their recognition site • Recombinant non-switchable and switch methylases were active in vitro and can be deployed as tools in synthetic biology and DNA assembly.

Characterization of a Type II L-Asparaginase from the Halotolerant Bacillus subtilis CH11.

L-asparaginases from bacterial sources have been used in antineoplastic treatments and the food industry. A type II L-asparaginase encoded by the N-truncated gene ansZP21 of halotolerant Bacillus subtilis CH11 isolated from Chilca salterns in Peru was expressed using a heterologous system in Escherichia coli BL21 (DE3)pLysS. The recombinant protein was purified using one-step nickel affinity chromatography and exhibited an activity of 234.38 U mg-1 and a maximum catalytic activity at pH 9.0 and 60 °C. The enzyme showed a homotetrameric form with an estimated molecular weight of 155 kDa through gel filtration chromatography. The enzyme half-life at 60 °C was 3 h 48 min, and L-asparaginase retained 50% of its initial activity for 24 h at 37 °C. The activity was considerably enhanced by KCl, CaCl2, MgCl2, mercaptoethanol, and DL-dithiothreitol (p-value < 0.01). Moreover, the Vmax and Km were 145.2 µmol mL-1 min-1 and 4.75 mM, respectively. These findings evidence a promising novel type II L-asparaginase for future industrial applications.

Synergistic action of thermophilic pectinases for pectin bioconversion into D-galacturonic acid.

Large amounts of pectin-rich biomass are generated worldwide yearly, which can be hydrolysed by pectinases to obtain bio-based chemical building blocks such as D-galacturonic acid (GalA). The aim of this work was to investigate thermophilic pectinases and explore their synergistic application in the bioconversion of pectic substrates into GalA. Two exo-polygalacturonases (exo-PGs) from Thermotoga maritima (TMA01) and Bacillus licheniformis (BLI04) and two pectin methylesterases (PMEs) from Bacillus licheniformis (BLI09) and Streptomyces ambofaciens (SAM10) were cloned and expressed in Escherichia coli BL21 (DE3), purified and fully characterised. These pectinases exhibited optimum activity at temperatures above 50 °C and good stability at high temperature (40-90 °C) for up to 24 h. Exo-PGs preferred non-methylated substrates, suggesting that previous pectin demethylation by PMEs was necessary to achieve an efficient pectin monomerisation into GalA. Synergistic activity between PMEs and exo-PGs was tested using pectin from apple, citrus and sugar beet. GalA was obtained from apple and citrus pectin in a concentration of up to 2.5 mM after 4 h reaction at 50 °C, through the combined action of BLI09 PME with either TMA01 or BLI04 exo-PGs. Overall, this work contributes to expand the knowledge of pectinases from thermophiles and provides further insights into their application in the initial valorisation of sustainable pectin-rich biomass feedstocks.

Obtención de hidrolizados proteicos de leguminosas usando una proteasa recombinante de Pseudomonas aeruginosa M211 / Obtaining protein hydrolysates from leguminous using a recombinant protease from Pseudomonas aeruginosa M211

El género Pseudomonas es una fuente importante de proteasas; sin embargo, su uso está restringido en la industria alimentaria. El clonaje permite aprovechar la capacidad catalítica de estas enzimas mediante su producción en microorganismos inocuos. Por otro lado, las leguminosas son fuentes ricas en proteínas, a partir de las cuales se pueden obtener compuestos con valor agregado mediante procesos de hidrólisis enzimática. En este estudio, se produjo y caracterizó una proteasa recombinante (PT4) alcalina y termoestable de Pseudomonas aeruginosa M211, para la obtención de hidrolizados proteicos de leguminosas. Para ello, el gen de la proteasa se clonó en el vector pJET1.2/blunt utilizando E. coli DHalfa como hospedero. El análisis de la secuencia nucleotídica parcial de la proteasa indicó un 99 % de similitud con Peptidasas de la Familia M4 de Pseudomonas aeruginosa. La enzima recombinante presentó un peso molecular de 80 kDa, demostró ser activa y estable en condiciones alcalinas y termófilas con un pH y temperatura óptimos de 8 y 60 °C, respectivamente, y fue inhibida por EDTA. Además, hidrolizó proteínas de semillas de Glycine max, Phaseolus lunatus, Lupinus mutabilis y Erythrina edulis, obteniéndose fracciones peptídicas menores a 40 kDa. Esta proteasa recombinante se podría utilizar en la elaboración de hidrolizados proteicos funcionales a partir proteínas de distintas fuentes y residuos agroalimentarios.

The genus Pseudomonas is an important source of proteases; however, in the food industry the use of this bacterium is restricted. Cloning allows for the use of the proteolytic activity of Pseudomonas proteases through their production in innocuous microorganisms. Leguminous are protein-rich sources from which value-added compounds can be obtained through enzymatic hydrolysis. In this study, an alkaline and thermostable recombinant protease (PT4) from Pseudomonas aeruginosa M211 was cloned and characterized in order to obtain protein hydrolysates from leguminous. Therefore, protease gene was cloned into the pJET1.2 / blunt vector using E. coli DHalpha as a host. Analysis of protease partial nucleotide sequence showed 99% homology with Peptidases M4 Family from Pseudomonas aeruginosa. The molecular weight of the recombinant enzyme was 80 kDa, it was active and stable under alkaline and thermophilic conditions, presented an optimum pH and temperature of 8 and 60 °C, respectively, and was inhibited by EDTA. In addition, it hydrolysed Glycine max, Phaseolus lunatus, Lupinus mutabilis y Erythrina edulis proteins, obtaining peptide fractions less than 40 kDa. This recombinant protease could be used in the elaboration of functional hydrolysates using protein from different sources and agricultural waste.

Production and Characterization of Extremophilic Proteinases From a New Enzyme Source, Barrientosiimonas sp. V9.

Microbial proteases are widely used as commercial enzymes, which have an active role in several industrial processes. The aim of this study was to investigate the production and properties of extracellular proteases from Barrientosiimonas sp. strain V9. The cultivation conditions for protease production were studied using different carbon and nitrogen sources. Maximum protease production was obtained in medium containing 25 g L-1 sucrose, 7 g L-1 KNO3, and initial pH 7.0 at 35 °C and 150 rpm during 72 h. Under these conditions, maximum proteolytic activity reached 1200 U mL-1. The enzyme extract showed optimum activity at 60 °C, pH 9.0, and was stable from 30 to 50 °C within a pH range from 4.0 to 10.0 and NaCl concentration up to 2.5 M. The enzyme was stable in the presence of EDTA, urea, Triton X-100 and laundry detergent (sodium lauryl sulfate as main component). The addition of 1% sodium dodecyl sulfate, Tween-80, or Tween-20 increased the activity by 183% and 119% respectively, while 2-mercaptoethanol reduced the activity to 71%. Casein zymogram analysis revealed three hydrolysis zones suggesting that Barrientosiimonas sp. V9 expresses proteases with molecular weights about 60, 45, and 35 kDa, which were inhibited in the presence of phenylmethylsulfonyl fluoride. Barrientosiimonas sp. V9 produces halotolerant serine proteases with great biotechnological potential.

Novel extremophilic proteases from Pseudomonas aeruginosa M211 and their application in the hydrolysis of dried distiller's grain with solubles.

Proteases are the most important group of industrial enzymes and they can be used in several fields including biorefineries for the valorization of industrial byproducts. In this study, we purified and characterized novel extremophilic proteases produced by a Pseudomonas aeruginosa strain isolated from Mauritia flexuosa palm swamps soil samples in Peruvian Amazon. In addition, we tested their ability to hydrolyze distillers dried grains with solubles (DDGS) protein. Three alkaline and thermophilic serine proteases named EI, EII, and EIII with molecular weight of 35, 40, and 55 kDa, respectively, were purified. EI and EIII were strongly inhibited by EDTA and Pefabloc being classified as serine-metalloproteases, while EII was completely inhibited only by Pefabloc being classified as a serine protease. In addition, EI and EII exhibited highest enzymatic activity at pH 8, while EIII at pH 11 maintaining almost 100% of it at pH 12. All the enzymes demonstrated optimum activity at 60°C. Enzymatic activity of EI was strongly stimulated in presence of Mn2+ (6.9-fold), EII was stimulated by Mn2+ (3.7-fold), while EIII was slightly stimulated by Zn2+ , Ca2+ , and Mg2+ . DDGS protein hydrolysis using purified Pseudomonas aeruginosa M211 proteases demonstrated that, based on glycine released, EIII presented the highest proteolytic activity toward DDGS. This enzyme enabled the release 63% of the total glycine content in wheat DDGS protein, 2.2-fold higher that when using the commercial Pronase®. Overall, our results indicate that this novel extremopreoteases have a great potential to be applied in DDGS hydrolysis. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2728, 2019.

Riesgos a úlceras por presión según Escala Norton en una población de ancianos de un servicio domiciliario de Lima / Risks for pressure ulcers according Scale Norton in aged patient at an institution of a domiciliary service of Lima

Objetivo: determinar el riesgo de úlceras por presión según Escala Norton en ancianos y clasificar el nivel de riesgo según proveedor de cuidados. Material y Métodos: estudio cuantitativo descriptivo tipo transversal; realizado en el Programa de Prestaciones de Atención Domiciliaria/PADOMI, del Seguro Social de Salud/EsSalud de un distrito de Lima. La población estuvo conformada por 833 ancianos, considerando una muestra aleatoria de 152 conforme criterios de inclusión. Los datos se recolectaron mediante visita domiciliaria, entrevista y observación utilizando una ficha de trabajo que incluía datos sociodemográficos del adulto mayor/cuidador y escala Norton; para analizar los datos se uso la estadística descriptiva. Resultados: el 53,3% de ancianos se encontraba en un rango de 80-89 años de edad, 69,8% eran de sexo femenino, 54,0% viudos y 34,9% asistidos por un cuidador informal. Asimismo, el 43,4% presentó un riesgo medio para úlceras por presión, siendo que el 65,1% presentaba estado físico general regular, estado mental apático 45,4% actividad disminuida 65,1%, camina con ayuda 61,8% e incontinencia ocasional 55,5%. Con relación a clasificación de riesgo según cuidador, destacó el riesgo medio en todos los proveedores, sin embargo, el 26,4% asistido por cuidador informal presentó riesgo muy alto y el 25,9% asistido por otro familiar riesgo alto. Conclusiones: gran proporción de ancianos tuvo riesgo medio para presentar úlceras por presión, siendo que las condiciones determinantes lo incrementan.

Objetive: to determinate the risk of pressure ulcers according Norton's Scale in aged patient and to classify the level of risk according to supplier of care. Materials and Methods: the quantitative descriptive study transverse type realized in Program of Presentations of Domiciliary Attention-PADOMI-of the Social Assurance of Health (EsSalud) of district of Lima. The population was shaped by 33 aged patient considering sample of 152; the information was gathered by means of domiciliary visit, interview and observation. Using a card of work, which was including information of supplier of care/the elder adult and the scale Norton; for to analyze the information, using the descriptive statistics. Results: 53.3% of the aged patient is in a range from 80 to 89 years, 69.8% is of the feminine sex, 54.0% widowers and 34.9% is attended by a keeper, likewise we have that 43.4% had an average risk to presenting pressure ulcers; being physical state regulate general 65.1% mental state apathetic 45.4%, activity diminished 65.1% walks with help 61.8% and incontinence occasional 55.5% with relation to classification of risk according to keeper, the average risk stood out in all the suppliers, nevertheless, 26.4% represented by informal keeper presented risk very high and 25.9% represented high risk by another relative. Conclusions: great proportion of aged patient had average risk to present pressure ulcers, being that the determining conditions increase this risk.

New indications for already-approved drugs: an analysis of regulatory review times.

A survey of the U.S. pharmaceutical industry was conducted to obtain data on the length of the review process for supplemental indications of already-approved new chemical entities (NCEs). Responses were received from 51 firms and covered supplemental indications of 348 NCEs that were approved during 1963 to 1988. Since extensive toxicity and safety evaluation would generally not be required for supplemental indication reviews, one would expect supplemental indications, on average, to be reviewed more quickly than applications for the associated original indications. The mean +/- standard deviation review time for the 172 supplemental indications in the sample is 21.5 +/- 18 months; the average review time for the associated 94 original indications is 23.5 +/- 18 months. The difference in average review times is not statistically significant. Analysis of review times for indications grouped by Food and Drug Administration (FDA) reviewing division showed a statistically significant difference between supplemental and associated original indication review times only in the cardio-renal division. In that division, average review times were longer for supplemental indications (25.6 vs. 19.3 mo; P less than .05). Analysis of time trends showed a significant increase in average supplemental indication review time for 1985 to 1988 approvals relative to the average associated original indication review time (P less than .01) and to average supplemental indication review time for earlier time periods (P less than .01). These results suggest the need for a close examination of the supplemental indication review policy of the FDA.