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Simultaneous Display of Multiple Foreign Peptides in the FliD Capping and FliC Filament Proteins of the Escherichia coli Flagellum 下载免费PDF全文
Katariina Majander Timo K. Korhonen Benita Westerlund-Wikstr?m 《Applied microbiology》2005,71(8):4263-4268
The bacterial flagellum is composed of more than 20 different proteins. The filament, which constitutes the major extracellular part of the flagellum, is built up of approximately 20,000 FliC molecules that assemble at the growing distal end of the filament. A capping structure composed of five FliD molecules located at the tip of the filament promotes polymerization of FliC. Lack of FliD leads to release of the subunits into the growth medium. We show here that FliD can be successfully used in bacterial surface display. We tested various insertion sites in the capping protein, and the optimal region for display was at the variable region in FliD. Deletion and/or insertion at other sites resulted in decreased formation of flagella. We further developed the technique into a multihybrid display system in which three foreign peptides are simultaneously expressed within the same flagellum, i.e., D repeats of FnBPA from Staphylococcus aureus at the tip and fragments of YadA from Yersinia enterocolitica as well as SlpA from Lactobacillus crispatus along the filament. This technology can have biotechnological applications, e.g., in simultaneous delivery of several effector molecules. 相似文献
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The moulting gel of silkmoths lacks proteolytic activity but contains an inactive form of the proteinases which are later found in the moulting fluid. These inactive enzymes are activatable in vitro by dilution, activation proceeding most rapidly at low ionic strength. Activation proceeds as a first-order process and is not autocatalytic. Approximately the full amount of proteinases ultimately found in moulting fluid are already present in the gel. Moulting gel does not inhibit the active proteinases of moulting fluid; moreover, the proteolytic activity elicited by dilution of the moulting gel does not disappear upon reconcentration. These observations suggest that the proteinases in moulting gel are not inhibited by a stable, dissociable inhibitor; they may be present either as compartmentalized active enzymes or as proenzymes. Several possible mechanisms for the in vivo activation at the time of gel to fluid transformation are discussed. 相似文献
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Antonio Bode Benita Casas Emilio Fernández Emilio Marañón Pablo Serret Manuel Varela 《Hydrobiologia》1996,341(3):225-234
Summary Chlorophyll-a and primary production on the euphotic zone of the N-NW Spanish shelf were studied at 125 stations between 1984 and 1992. Three geographic areas (Cantabrian Sea, Rías Altas and Was Baixas), three bathymetric ranges (20 to 60 m, 60 to 150 m and stations deeper than 200 m), and four oceanographic stages (spring and autumn blooms, summer upwelling, summer stratification and winter mixing) were considered. One of the major sources of variability of chlorophyll and production data was season. Bloom and summer upwelling stages have equivalent mean and maximum values. Average chlorophyll-a concentrations approximately doubled in every step of the increasing productivity sequence: winter mixing — summer stratification — high productivity (upwelling and bloom) stages. Average primary production rates increased only 60% in the described sequence. Mean (± sd) values of chlorophyll-a and primary production rates during the high productivity stages were 59.7 ± 39.5 mg Chl-a m–2 and 86.9 ± 44.0 mg C m–2 h–1, respectively. Significant differences in both chlorophyll and primary production resulted between geographic areas in most stages. Only 27 stations showed the effects of the summer upwelling that affected coastal areas in the Cantabrian Sea and Rías Baixas shelf, but also shelf-break stations in the Rías Altas area. The Rías Baixas area had lower chlorophyll than both the Rías Altas and the Cantabrian Sea areas during spring and autumn blooms, but higher during summer upwelling events. On the contrary, primary production rates were higher in the Rías Baixas area during blooms in spring and autumn. Mid-shelf areas showed the highest chlorophyll concentrations during high productivity stages, probably due to the existence of frontal zones in all geographic areas considered. The estimated phytoplankton growth rates were comparable to those of other coastal upwelling systems, with average values lower than the maximum potential growth rates. Doubling rates for upwelling and stratification stages in the northern and Rías Altas shelf areas were equivalent, despite larger biomass accumulations during upwelling events. Low turnover rates of the existing biomass in the Rías Baixas shelf in upwelling stages suggests that the accumulation of phytoplankton was due mainly to the export from the highly productive rías, while the contribution of in situ production to these accumulations was relatively lower. 相似文献
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Ribonucleoside diphosphate reductase activity is determined in centrifuged homogenates by following the conversion of cytosine ribonucleotide to cytosine deoxyribonucleotide. The enzymatic reaction is measured by monitoring the radioactivity of the reaction products separated by thin layer chromatography on PEI-cellulose plates. The method is rapid and permits the simultaneous processing of multiple samples. 相似文献
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Hunter Elena Percival Benita Ahmad Zeeshan Chang Ming-Wei Hunt John A. Tasker Séverine De Risio Luisa Wilson Philippe B. 《Molecular and cellular biochemistry》2021,476(11):4133-4137
Molecular and Cellular Biochemistry - Chronic kidney disease (CKD) is a renal dysfunction that can lead to high rates of mortality and morbidity, particularly when coupled with late diagnosis. CKD... 相似文献
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Studies using HeLa cells expressing 5-HT7 receptors showed that detergent resistant membranous lipid rafts purified by sucrose gradient centrifugation contained 5-HT7 receptors and caveolin-1. Caveolin-1 siRNA-mediated knockdown or serotonin (5-HT) treatment caused significant reductions of maximum [3H]5-HT binding to 5-HT7 receptors and total immunoreactivity of membranous 5-HT7 receptors in intact cells. Co-treatment with 5-HT, caveolin-1 siRNA and methyl-beta-cyclodextrin had no additive effects on reducing maximum binding of [3H]5-HT to 5-HT7 receptors. 5-HT-mediated reduction of [3H]5-HT binding to 5-HT7 receptors was counteracted by genistein, but not by sucrose. Caveolin-1, specifically localized in cholesterol-enriched lipid rafts, appears to regulate constitutive and agonist-stimulated cell surface levels of 5-HT7 receptors via a clathrin-independent mechanism. 相似文献