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131.
Bujacz A Jedrzejczak-Krzepkowska M Bielecki S Redzynia I Bujacz G 《The FEBS journal》2011,278(10):1728-1744
We solved the 1.8 ? crystal structure of β-fructofuranosidase from Bifidobacterium longum KN29.1 - a unique enzyme that allows these probiotic bacteria to function in the human digestive system. The sequence of β-fructofuranosidase classifies it as belonging to the glycoside hydrolase family 32 (GH32). GH32 enzymes show a wide range of substrate specificity and different functions in various organisms. All enzymes from this family share a similar fold, containing two domains: an N-terminal five-bladed β-propeller and a C-terminal β-sandwich module. The active site is located in the centre of the β-propeller domain, in the bottom of a 'funnel'. The binding site, -1, responsible for tight fructose binding, is highly conserved among the GH32 enzymes. Bifidobacterium longum KN29.1 β-fructofuranosidase has a 35-residue elongation of the N-terminus containing a five-turn α-helix, which distinguishes it from the other known members of the GH32 family. This new structural element could be one of the functional modifications of the enzyme that allows the bacteria to act in a human digestive system. We also solved the 1.8 ? crystal structure of the β-fructofuranosidase complex with β-D-fructose, a hydrolysis product obtained by soaking apo crystal in raffinose. 相似文献
132.
Marek K. Zdanowski Magdalena J. Żmuda-Baranowska Piotr Borsuk Aleksander Świątecki Dorota Górniak Dorota Wolicka Katarzyna M. Jankowska Jakub Grzesiak 《Polar Biology》2013,36(4):511-527
Glacier forelands are excellent sites in which to study microbial succession because conditions change rapidly in the emerging soil. Development of the bacterial community was studied along two transects on lateral moraines of Ecology Glacier, King George Island, by culture-dependent and culture-independent approaches (denaturating gradient gel electrophoresis). Environmental conditions such as cryoturbation and soil composition affected both abundance and phylogenetic diversity of bacterial communities. Microbiocenosis structure along transect 1 (severe cryoturbation) differed markedly from that along transect 2 (minor cryoturbation). Soil physical and chemical factors changed along the chronosequence (time since exposure) and influenced the taxonomic diversity of cultivated bacteria, particularly along transect 2. Arthrobacter spp. played a pioneer role and were present in all soil samples, but were most abundant along transect 1. Cultivated bacteria isolated from transect 2 were taxonomically more diverse than those cultivated from transect 1; those from transect 1 tended to express a broader range of enzyme and assimilation activities. Our data suggest that cryoturbation is a major factor in controlling bacterial community development in postglacial soils, shed light on microbial succession in glacier forelands, and add a new parameter to models that describe succession phenomena. 相似文献
133.
Mueller R Rachwal S Tedder ME Li YX Zhong S Hampson A Ulas J Varney M Nielsson L Rogers G 《Bioorganic & medicinal chemistry letters》2011,21(13):3927-3930
AMPA receptors (AMPARs) are an important therapeutic target in the CNS. A series of substituted benzoxazinone derivatives with good to very good in vitro activity as positive allosteric AMPAR modulators was synthesized and evaluated. The appropriate substituent choice on the benzoxazinone fragment improved the affinity towards the AMPA receptor significantly in comparison to our lead molecule CX614. 相似文献
134.
In this work a simple kinetic model to describe the biosynthesis of lovastatin by Aspergillus terreus ATCC 20542 was proposed. Several series of experiments were conducted at different media compositions. The concentrations of C- and N-sources were changed over a wide range and so were the initial biomass concentrations. From these runs the relationships ruling the substrates uptake, biomass and product formation were learnt. Lovastatin biosynthesis appeared to be partly growth associated. The inhibitive effect of organic nitrogen on lovastatin biosynthesis was found and lactose appeared to be an important limiting substrate in the formation of lovastatin. The parameters of the model were evaluated on the basis of the kinetic data obtained in the separate experiments made in triplicate at two chosen media compositions. Other results obtained at different media compositions were independent of the ones mentioned above and used for the verification of the model. The validity of the model was also examined for the lactose-fed fed-batch run. Finally, a sensitivity analysis of the model parameters was performed. The formulated model, although relatively simplified, described the experimental data quite well and could be regarded as the background for further attempts to mathematically describe the process of lovastatin biosynthesis. 相似文献
135.
The simultaneous biosynthesis of lovastatin (mevinolinic acid) and (+)-geodin by Aspergillus terreus ATCC 20542 with regard to the medium composition, i.e. the concentrations of carbon and nitrogen source, was described in this paper. A. terreus is a lovastatin producer but the formation of lovastatin was accompanied by the significant amounts of (+)-geodin, when the elevated concentration of carbon source (lactose) was still present in the medium in the idiophase and nitrogen source (yeast extract) was deficient. It was observed for runs, in which the higher (above 20 g l(-1)) initial lactose concentration was applied or when the nitrogen deficiency led to the decrease of biomass content in the system. In contrast to lovastatin, there was not optimum initial concentration of yeast extract, as its lowest tested initial concentration (2 g l(-1)) led to the highest (+)-geodin volumetric formation rates and final yield. What is more, even higher final (+)-geodin concentrations were achieved at elevated initial lactose concentration (40 g l(-1)) and in the lactose-fed fed-batch run. In the fed-batch run lovastatin concentration increased significantly too, as this metabolite formation is also carbon source dependent. Finally, (+)-geodin occurred to be a metabolite, whose formation, in contrast to lovastatin, is non-growth associated. 相似文献
136.
137.
Anna D. Grabowska Ewa Wywia? Stanislaw Dunin-Horkawicz Anna M. ?asica Marc M. S. M. W?sten Anna Nagy-Staroń Renata Godlewska Katarzyna Bocian-Ostrzycka Katarzyna Pieńkowska Pawe? ?aniewski Janusz M. Bujnicki Jos P. M. van Putten E. Katarzyna Jagusztyn-Krynicka 《PloS one》2014,9(9)
Background
Bacterial Dsb enzymes are involved in the oxidative folding of many proteins, through the formation of disulfide bonds between their cysteine residues. The Dsb protein network has been well characterized in cells of the model microorganism Escherichia coli. To gain insight into the functioning of the Dsb system in epsilon-Proteobacteria, where it plays an important role in the colonization process, we studied two homologs of the main Escherichia coli Dsb oxidase (EcDsbA) that are present in the cells of the enteric pathogen Campylobacter jejuni, the most frequently reported bacterial cause of human enteritis in the world.Methods and Results
Phylogenetic analysis suggests the horizontal transfer of the epsilon-Proteobacterial DsbAs from a common ancestor to gamma-Proteobacteria, which then gave rise to the DsbL lineage. Phenotype and enzymatic assays suggest that the two C. jejuni DsbAs play different roles in bacterial cells and have divergent substrate spectra. CjDsbA1 is essential for the motility and autoagglutination phenotypes, while CjDsbA2 has no impact on those processes. CjDsbA1 plays a critical role in the oxidative folding that ensures the activity of alkaline phosphatase CjPhoX, whereas CjDsbA2 is crucial for the activity of arylsulfotransferase CjAstA, encoded within the dsbA2-dsbB-astA operon.Conclusions
Our results show that CjDsbA1 is the primary thiol-oxidoreductase affecting life processes associated with bacterial spread and host colonization, as well as ensuring the oxidative folding of particular protein substrates. In contrast, CjDsbA2 activity does not affect the same processes and so far its oxidative folding activity has been demonstrated for one substrate, arylsulfotransferase CjAstA. The results suggest the cooperation between CjDsbA2 and CjDsbB. In the case of the CjDsbA1, this cooperation is not exclusive and there is probably another protein to be identified in C. jejuni cells that acts to re-oxidize CjDsbA1. Altogether the data presented here constitute the considerable insight to the Epsilonproteobacterial Dsb systems, which have been poorly understood so far. 相似文献138.
139.
Talbot NC Sparks WO Powell AM Kahl S Caperna TJ 《In vitro cellular & developmental biology. Animal》2012,48(1):1-11
Feeder cells of irradiated mouse fibroblasts are commonly used for, and are generally necessary for, the in vitro maintenance
and growth of many fastidious cell types, particularly embryonic stem cells or induced pluripotent stem cells. Quantitative
and semiquantitative immunoassays of conditioned media were performed to identify some of the soluble cytokines, chemokines,
protein hormones, and cell matrix/adhesion molecules that are elaborated from two commonly used feeder cells, STO and CF-1.
Among those quantitatively assayed, the most abundant cytokine proteins expressed by the feeder cells were activin A, hepatocyte
growth factor (HGF), insulin-like growth factor 1, insulin-like growth factor 2, insulin-like growth factor binding protein
(IGFBP)-6, macrophage colony-stimulating factor (a.k.a. CSF-1), and pigment epithelium-derived factor (a.k.a. serine protease
inhibitor, clade F, member 1). CF-1 cells expressed ten times more activin A than STO cells and also produced larger amounts
of interleukin-6 and IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-5. Conversely, STO cell produced almost ten times more HGF and five
times more stem cell factor (a.k.a. c-kit ligand) than CF-1 cells. Assayed semiquantitatively, relatively large amounts of
chemokines were produced by both feeder cells including fractalkine (CX3CL1), interferon-inducible protein 10 (a.k.a. CXCL10
and cytokine-responsive gene-2, CRG-2), monocyte chemotactic protein (MCP)-1 (a.k.a. CCL2 and junctional epithelium chemokine
(JE), MCP-5/CCL12), keratinocyte-derived chemokine (a.k.a. CXCL1 and growth-related oncogene alpha, GROα), nephroblastoma
overexpressed gene (CCN3, IGFBP-9), stromal cell-derived factor 1 (CXCL12), and serpin E1 (PAI-1). In contrast to one another,
STO produced more CXCL16 than CF-1 cells, and CF-1 cell produced more MCP-5 (CCL12), macrophage inflammatory protein (MIP)-1α
(CCL3), MIP-1β (CCL4), pentraxin-3 (TSG-14), and platelet factor-4 (CXCL4) than STO cells. Soluble adhesion molecule, sICAM
(ICAM-1, CD54), was expressed by CF-1 cells, but not STO cells, and similarly, the cell matrix-associated molecules endocan
(endothelial cell-specific molecule 1), endostatin (collagen XVIII), and matrix metalloproteinase 3 were expressed more by
CF-1 cells. Tissue inhibitor of metalloproteinases 1 was robustly expressed by both feeder cells. Other proteins primarily
detected from CF-1 cells included retinol-binding protein 4 and FGF21, while STO cells secreted more interferon gamma. Both
feeder cells produced no or low amounts of LIF, tumor necrosis factor alpha, vascular endothelial growth factor (VEGF), VEGF-B,
prolactin, various interleukins, fibroblast growth factor (FGF)-1, FGF-2, FGF-7, EGF, HB-EGF, and amphiregulin. The results
may explain some of the cell growth and maintenance responses by various types of cells co-cultured on STO or CF-1 feeder
cells. 相似文献
140.
Tomasz Hura Stanisław Grzesiak Katarzyna Hura Maciej Grzesiak Andrzej Rzepka 《Acta Physiologiae Plantarum》2006,28(5):433-443
The studies were carried out in order to estimate differences in the physiological state between triticale and maize plants
subjected to drought stress followed by rehydration. The physiological state of the plants was evaluated by measurements of
leaf water potential, net photosynthesis, transpiration and stomatal conductance. Spectrofluorimetric methods for the study
of blue, green and red fluorescence were applied.
We observed that the soil drought induced a greater water loss in triticale leaves than in maize and consequently caused greater
injuries to the photosynthetic apparatus. Moreover, triticale plant recovery was slower than in maize plants during the rehydration
phase. The effect was probably connected with the higher functional and structural disorganisation of the photosynthetic apparatus
observed during drought stress in triticale. Water stress is responsible for damages to photosystem PS II. The worst light
utilisation in photosynthetic light conversion was recorded as an increase in the intensity of red fluorescence. Drought stress
induced a strong increase in the intensity of blue and green fluorescence in the studied species and it was still high in
maize plants during the first day of rehydration. Increase in the intensity of blue and green fluorescence in maize seems
to be the effect of the photoprotection mechanism which prevents damage to PS II through utilisation of excess energy. 相似文献