A glucuronoxylan-specific xylanase from a new Paenibacillus favisporus strain isolated from tropical soil of Brazil

A new xylanolytic strain, Paenibacillus favisporus CC02-N2, was isolated from sugarcane plantation fields in Brazil. The strain had a xylan-degrading system with multiple enzymes, one of which, xylanase Xyn30A, was identified and characterized. The enzyme is a single-domain xylanase belonging to family 30 of the glycosyl hydrolases (GH30). Xyn30A shows high activity on glucuronoxylans, with a Vmax of 267.2 U mg-1, a Km of 4.0 mg/ml, and a kcat of 13,333 min-1 on beechwood xylan, but it does not hydrolyze arabinoxylans. The three-dimensional structure of Xyn30A consists of a common (β/α) 8 barrel linked to a side-chain-associated β-structure, similar to previously characterized GH30 xylanases. The hydrolysis products from glucuronoxylan were methylglucuronic-acid-substituted xylooligomers (acidic xylooligosaccharides). The enzyme bound to insoluble xylan but not to crystalline cellulose. Our results suggest a specific role for Xyn30A in xylan biodegradation in natural habitats. The enzyme is a good candidate for the production of tailored xylooligosaccharides for use in the food industry and in the biotechnological transformation of biomass (AU)

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Screening, isolation, and characterization of glycosyl-hydrolase-producing fungi from desert halophyte plants

Fungal strains naturally occurring on the wood and leaves of the salt-excreting desert tree Tamarix were isolated and characterized for their ability to produce cellulose- and starch- degrading enzymes. Of the 100 isolates, six fungal species were identified by ITS1 sequence analysis. No significant differences were observed among taxa isolated from wood samples of different Tamarix species, while highly salt-tolerant forms related to the genus Scopulariopsis (an anamorphic ascomycete) occurred only on the phylloplane of T. aphylla. All strains had cellulase and amylase activities, but the production of these enzymes was highest in strain D, a Schizophyllum-commune- related form. This strain, when grown on pretreated Tamarix biomass, produced an enzymatic complex containing levels of filter paperase (414 ± 16 IU/ml) that were higher than those of other S. commune strains. The enzyme complex was used to hydrolyze different lignocellulosic substrates, resulting in a saccharification rate of pretreated milk thistle (73.5 ± 1.2 %) that was only 10 % lower than that obtained with commercial cellulases. Our results support the use of Tamarix biomass as a useful source of cellulolytic and amylolytic fungi and as a good feedstock for the economical production of commercially relevant cellulases and amylases (AU)

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Glicopatología, glicoterapéutica y marcadores tumorales glicánicos / Glicopatology, Glycotherapeutic and Glycan Tumor Markers

La desregulación (por causas genéticas o adquiridas) de la actividad de ciertas glicosiltransferasas, glicosidasas o isomerasas que catalizan los procesos metabólicos en que participan los glicoconjugados - moléculas resultantes de la unión entre glúcidos y prótidos o glúcidos y lípidos - ocasiona anomalías en la estructura química de estos compuestos, por originarse moléculas (generalmente truncadas o con ramificación aberrante) incapaces de efectuar sus funciones biológicas normales. Surgen así anomalías por almacenamiento, provocadas por disfunción o ausencia de la actividad catabólica a cargo de enzimas lisosómicas ("Lysosomal Storage Disorders") o desórdenes congénitos de glicosilación ("Congenital disorders of Glycosylation, CDG") que afectan a la biosíntesis de estas sustancias. La Glicopatología resultante se halla estrechamente vinculada con procesos infecciosos por: virus (gripe, SIDA, etc.), bacterias (E. coli, Streptococcus sp., Helicobacter pylori, etc.), hongos o protozoos, así como con procesos cancerosos o inmunitarios(AU)

The disregulation (due to genetic or acquired factors) of the activity of certain glycosyltransferases, glicosidases or isomerases which catalyse the metabolic processes related to the glycoconjugates - molecules resulting of the link between carbohydrates and proteins or between carbohydrates and lipids - produces anomalies in the chemical structure of these compounds (generally truncated structures or aberrant chain branching) who preclude their normal biological functions. So, Lysosomal Storage Disorders (by abnormalities in the catabolic way) or Congenital Disorders of Glycosylation (by abnormalities in the biosynthetic route) arise. Infectious processes, either by viruses (influenza, AIDS, etc.) or bacteria (E. coli, Streptococcus sp., Helicobacter pylori, etc.) or fungi or protozoa, as well as cancer or immune processes, belong to the chapter of the Glycopathology(AU)

Efecto de FZ sobre el control glucémico en ratas diabéticas / FZ effect on the glucemic control of diabetic rats

El producto FZ presenta selectividad para la captura de glucosa del medio, mostrando un efecto similar al de medicamentos conocidos como antihipergliemiantes, entre otros la Acarbosa, el Fibraguar y el Miglitol. OBJETIVO. Demostrar el potencial terapéutico de (FZ) sobre un modelo experimental de diabetes en ratas. MATERIAL Y MÉTODO. Se utilizaron 40 ratas Wistar de 60 días de nacidas. A las mismas se las indujo la diabetes a través de la administración de estreptozotocina. Los niveles de glucemia fueron medidos tres días después de la inyección, de los animales que resultaron hiperglucémicos se repartieron en dos grupos homogéneos según peso y niveles de glucemia. Se realizó una prueba de tolerancia a la glucosa provocando una hiperglucemia por vía oral se administró por vía oral una carga de 1 y 5g de glucosa por Kg. Un minuto después se administró al grupo bajo tratamiento una dosis de FZ de 0.1 mg por kg de peso de la rata, se determinaron con un Glucómetro los niveles de glucemia en el tiempo 0 y después del tratamiento 15, 30, 45, 60, 90 y 120 minutos. RESULTADOS. El efecto antihiperglucemiante se observó a través de la glucemia y se calculó el área bajo la curva .Se observó que los grupos bajo tratamiento con FZ presentaron valores inferiores de las áreas bajo la curva que el grupo control. CONCLUSIONES. El tratamiento con FZ a las ratas hiperglucémicas disminuyó las áreas bajo la curva de absorción de glucosa (AU)

INTRODUCTION. FZ captures glucose selectively, showing a similar effect like anti-hiperglucemiants, (Acarbosa, Fibraguar and the Miglitol). OBJECTIVE. To demonstrate the therapeutic potential of FZ on an experimental model of diabetes rats. MATERIAL AND METHOD. Forty Wistar rats of 60 days born were utilized. The diabetes was induced by Streptozotocin administration. The glycaemia levels were measured three days after the injection; the animals that proved to be hyperglycaemic were distributed in two homogeneous groups according to weight and glucose levels. A load of 1 and 5g of glucose for Kg were orally administrated, after glucose administration FZ treatment group dose of 0.1 mg for kg of weight of the rat was also administrated. We determined glucose levels in time after the treatment 15, 30, 45, 60, 90 and 120 minutes. RESULTS. The anti-hiperglucemiant effect was observed through the glucose blood levels and the calculated area under curve. Lower values and curved areas were observed in the FZ treatment than control group. Conclusions: The FZ treatment of rats with high glucose levels in blood reduces the areas under the curve of glucose absorption (AU)

Hydration of vinyl ether groups by unsaturated glycoside hydrolases and their role in bacterial pathogenesis

Many pathogenic microorganisms invade mammalian and/or plant cells by producing polysaccharide-degrading enzymes (lyases and hydrolases). Mammalian glycosaminoglycans and plant pectins that form part of the cell surface matrix are typical targets for these microbial enzymes. Unsaturated glycoside hydrolase catalyzes the hydrolytic release of an unsaturated uronic acid from oligosaccharides, which are produced through the reaction of matrix-degrading polysaccharide lyase. This enzymatic ability suggests that unsaturated glycoside hydrolases function as virulence factors in microbial infection. This review focuses on the molecular identification, bacterial distribution, and structure/function relationships of these enzymes. In contrast to general glycoside hydrolases, in which the catalytic mechanism involves the retention or inversion of an anomeric configuration, unsaturated glycoside hydrolases uniquely trigger the hydrolysis of vinyl ether groups in unsaturated saccharides but not of their glycosidic bonds (AU)

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Candida albicans UBI3 and UBI4 promoter regions confer differential regulation of invertase production to Saccharomyces cerevisiae cells in response to stress

Candida albicans ubiquitin genes UBI3 and UBI4 encode a ubiquitin-hybrid protein involved in ribosome biogenesis and polyubiquitin, respectively. In this work we show that UBI3 and UBI4 promoter regions confer differential expression consistent with the function of their encoded gene products. Hybrid genes were constructed containing the SUC2 coding region under the control of UBI3 or UBI4 promoters in the yeast vector pLC7. Invertase production in Saccharomyces cerevisiae transformants was differentially regulated: the UBI4 promoter was induced by stress conditions (thermal upshift and/or starvation) whereas the UBI3 promoter conferred constitutive invertase production in growing yeast cells. These results indicate that the UBI4 promoter is regulated by stress-response signaling pathways, whereas the UBI3 promoter is controlled according to the requirement for protein synthesis to support cell growth (AU)

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