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151.
Ana Casa?al Ulrich Zander Cristina Mu?oz Florine Dupeux Irene Luque Miguel Angel Botella Wilfried Schwab Victoriano Valpuesta José A. Marquez 《The Journal of biological chemistry》2013,288(49):35322-35332
Pathogenesis-related 10 (PR-10) proteins are involved in many aspects of plant biology but their molecular function is still unclear. They are related by sequence and structural homology to mammalian lipid transport and plant abscisic acid receptor proteins and are predicted to have cavities for ligand binding. Recently, three new members of the PR-10 family, the Fra a proteins, have been identified in strawberry, where they are required for the activity of the flavonoid biosynthesis pathway, which is essential for the development of color and flavor in fruits. Here, we show that Fra a proteins bind natural flavonoids with different selectivity and affinities in the low μm range. The structural analysis of Fra a 1 E and a Fra a 3-catechin complex indicates that loops L3, L5, and L7 surrounding the ligand-binding cavity show significant flexibility in the apo forms but close over the ligand in the Fra a 3-catechin complex. Our findings provide mechanistic insight on the function of Fra a proteins and suggest that PR-10 proteins, which are widespread in plants, may play a role in the control of secondary metabolic pathways by binding to metabolic intermediates. 相似文献
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153.
Odile Francesca Restaino Irene di Lauro Donatella Cimini Elisabetta Carlino Mario De Rosa Chiara Schiraldi 《Applied microbiology and biotechnology》2013,97(4):1699-1709
Chondroitin sulfate is a well-known bioactive molecule, widely used as an anti-osteoarthritis drug, that is nowadays mainly produced by animal tissue sources with unsafe extraction procedures. Recent studies have explored an integrated biotechnological–chemical strategy to obtain a chondroitin sulfate precursor from Escherichia coli K4 capsular polysaccharide, demonstrating the influence of environmental and growth conditions on capsule synthesis. In this research work, the flexibility of the strain biosynthetic machinery was investigated to enhance the K4 capsular polysaccharide production by supplementing the growth medium with the monosaccharides (glucuronic acid, galactosamine and fructose) that constitute the chain. Shake flask experiments were performed by adding the sugars singularly or together, by testing monosaccharide different concentrations and times of addition and by observing the bacterial sugar consumption. A K4 capsular polysaccharide production enhancement, compared to the control, was observed in all cases of supplementation and, in particular, significant 68 and 57 % increases were observed when adding 0.385 mM glucuronic acid plus galactosamine or 0.385 mM fructose, respectively. Increased expression levels of the gene kfoC, coding for a K4 polymerase, evaluated in different growth conditions, confirmed the results at the molecular level. Furthermore, batch fermentations, performed in lab-scale reactors (2 L), allowed to double the K4 capsular polysaccharide production values obtained in shake flask conditions, by means of a strict control of the growth parameters. 相似文献
154.
Isabella V. Miller Graca Raposo Ulrich Welsch Olivia Prazeres da Costa Uwe Thiel Maria Lebar Martina Maurer Hans‐Ulrich Bender Irene von Luettichau Günther H. S. Richter Stefan Burdach Thomas G. P. Grunewald 《Biology of the cell / under the auspices of the European Cell Biology Organization》2013,105(7):289-303
155.
Filomena Sica Andrea Pica Antonello Merlino Irene Russo Krauss Carmine Ercole Delia Picone 《FEBS letters》2013
Bovine seminal ribonuclease (BS-RNase) acquires an interesting anti-tumor activity associated with the swapping on the N-terminal. The first direct experimental evidence on the formation of a C-terminal swapped dimer (C-dimer) obtained from the monomeric derivative of BS-RNase, although under non-native conditions, is here reported. The X-ray model of this dimer reveals a quaternary structure different from that of the C-dimer of RNase A, due to the presence of three mutations in the hinge peptide 111–116. The mutations increase the hinge peptide flexibility and decrease the stability of the C-dimer against dissociation. The biological implications of the structural data are also discussed. 相似文献
156.
Irene Stranden Løvdal Per Einar Granum Jan Thomas Rosnes Trond Løvdal 《Antonie van Leeuwenhoek》2013,103(3):693-700
The time/temperature profiles experienced by spores on the track from their natural sporulation environment to consumable food products may be highly diverse. Temperature has been documented as an important factor that may activate spores, i.e. potentiates spores to germinate. There is, however, limited knowledge about the relationship between the expected temperature history and the subsequent germination characteristics of bacterial spores. We show here that the germination rate of five different Bacillus spore populations, represented by strains of Bacillus cereus, Bacillus weihenstephanensis, Bacillus pumilus, Bacillus licheniformis and Bacillus subtilis could be increased following 1 week storage at moderately elevated temperatures, 30–33 °C, compared to spores stored at 3–8 °C. The results imply that spores contamination routes to foods, specifically the temperature history, could be highly relevant data in predictive modeling of food spoilage and safety. Activation at these moderately elevated temperatures may be a native form of spore activation in their natural habitats, knowledge that also could be useful in development of decontamination strategies for mildly heated foods. 相似文献
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158.
Anna M. Romaní Stefano Amalfitano Joan Artigas Stefano Fazi Sergi Sabater Xisca Timoner Irene Ylla Annamaria Zoppini 《Hydrobiologia》2013,719(1):43-58
River and stream biofilms in mediterranean fluvial ecosystems face both extreme seasonality as well as arrhythmic fluctuations. The hydrological extremes (droughts and floods) impose direct changes in water availability but also in the quantity and quality of organic matter and nutrients that sustain the microbial growth. This review analyzes how these ecological pulses might determine unique properties of biofilms developing in mediterranean streams. The paper brings together data from heterotrophic and autotrophic community structure, and extracellular enzyme activities in biofilms in mediterranean streams. Mediterranean stream biofilms show higher use of peptides during the favorable period for epilithic algae development (spring), and preferential use of cellulose and hemicellulose in autumn as a response to allochthonous input. The drying process causes the reduction in bacterial production and chlorophyll biomass, but the rapid recovery of both autotrophs and heterotrophs with rewetting indicates their adaptability to fluctuations. Bacteria surviving the drought are mainly associated with sediment and leaf litter which serve as “humid refuges”. Some algae and cyanobacteria show resistant strategies to cope with the drought stress. The resistance to these fluctuations is strongly linked to the streambed characteristics (e.g., sediment grain size, organic matter accumulation, nutrient content). 相似文献
159.
Sandra Oramas-Royo Concepción Torrejón Irene Cuadrado Rita Hernández-Molina Sonsoles Hortelano Ana Estévez-Braun Beatriz de las Heras 《Bioorganic & medicinal chemistry》2013,21(9):2471-2477
In the present study, a series of metallic complexes of the 1,4-naphthoquinone lawsone (2–6) were synthesized and evaluated for potential cytotoxicity in a mouse leukemic macrophagic RAW 264.7 cell line. Cell viability was determined by the MTT assay. Significant growth inhibition was observed for the copper complex (4) with an IC50 value of 2.5 μM. This compound was selected for further evaluation of cytotoxic activity on several human cancer cells including HT-29 (human colorectal adenocarcinoma), HepG2 (human hepatocellular carcinoma) and HeLa, (human cervical adenocarcinoma cells). Significant cell viability decrease was also observed in HepG2 cells. The apoptotic potential of this complex was evaluated in these cells. Compound 4 induced apoptosis by a mechanism that involves the activation of caspases 3, 8 and 9 and modulation of apoptotic-related proteins such as Bax, Bad, and p53. These results indicate that metal complexes of lawsone derivatives, in particular compound 4, might be used for the design of new antitumoral agents. 相似文献
160.
Irene Friligou Fabio Rizzolo Francesca Nuti Theodore Tselios Maria Evangelidou Mary Emmanouil Maria Karamita John Matsoukas Mario Chelli Paolo Rovero Anna Maria Papini 《Bioorganic & medicinal chemistry》2013,21(21):6718-6725
Multiple antigenic peptide (MAP) systems are dendrimeric structures bearing multiple copies of identical or different peptide epitopes, and they have been demonstrated to show enhanced immunogenicity. Herein, we report the direct (divergent) and indirect (convergent) synthesis, using contemporary synthetic approaches, of a di-branched antigenic peptide (di-BAP) containing the immunodominant epitope MBP(83–99), which is implicated in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). The direct synthesis (di-BAP 1) was performed using microwave irradiation. The indirect synthesis (di-BAP 2) was carried out performing an efficient chemoselective coupling reaction through the formation of a thioether bond. Both di-BAPs were conjugated to polysaccharide mannan since mannosylation is a promising technique to achieve modulation in immune response. The conjugation was achieved through free amino groups of both di-BAPs via the formation of Schiff bases. The mannan-conjugated di-BAPs were further evaluated in vivo in a prophylactic vaccination protocol, prior to EAE induction in Lewis rats. 相似文献