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1.
Identification of two amino acids in the hemagglutinin glycoprotein of measles virus (MV) that govern hemadsorption, HeLa cell fusion, and CD46 downregulation: phenotypic markers that differentiate vaccine and wild-type MV strains. 总被引:9,自引:9,他引:0 下载免费PDF全文
V Lecouturier J Fayolle M Caballero J Carabaa M L Celma R Fernandez-Muoz T F Wild R Buckland 《Journal of virology》1996,70(7):4200-4204
We have used site-directed mutagenesis of the hemagglutinin (H) glycoprotein of measles virus (MV) to investigate the molecular basis for the phenotypic differences observed between MV vaccine strains and recently isolated wild-type MV strains. The former downregulate CD46, the putative cellular receptor of MV, are positive for hemadsorption, and are fusogenic in HeLa cells, whereas the latter are negative for these phenotypic markers. CD46 downregulation in particular, could have profound consequences for the immunopathology of MV infection, as this molecule protects the cell from complement lysis. Mutagenesis of two amino acids, valine and tyrosine at positions 451 and 481, respectively, in the H protein from the vaccine-like Hallé MV strain to their counterparts, glutamate and asparagine, in the H protein from the wild-type Ma93F MV strain (creating the V451E/Y481N double mutation) abrogated CD46 downregulation, HeLa cell fusion, and hemadsorption. The converse double mutagenesis of the Ma93F H protein (E451V/N481Y) transferred the CD46-downregulating, fusogenic, and hemadsorption functions to this protein. The data provide the first mapping study of the functional domains of MV H. The consequences of these results for MV vaccine design and the role of CD46 in MV infection are discussed. 相似文献
2.
V Lecouturier A Rizzitelli J Fayolle L Daviet F T Wild R Buckland 《Biochemical and biophysical research communications》1999,264(1):268-275
CD46 acts as a cellular receptor for vaccine strains of measles virus (MV). The MV/CD46 interaction-mediated by the MV attachment glycoprotein, the hemagglutinin (H)-not only facilitates infection but also induces CD46 downregulation. A conflict of opinion exists as to whether a single MVH binding site on CD46, or two separate sites, facilitates the two phenomena. To investigate this conundrum we first tested and compared a panel of CD46-specific monoclonal antibodies (mAbs) for their capacity to block both processes. One (mAb 13/42) abrogated both MV fusion and CD46 downregulation. Mutation of an amino acid (arg59 in the SCR1 of CD46) essential for the epitope of mAb 13/42 resulted in the abrogation of both CD46 downregulation and viral fusion. This strongly suggests that the same MV binding site on CD46 is responsible for both CD46 downregulation and MV infection. 相似文献
3.
Benjelloun H Rochex A Lecouturier D Dechemi S Lebeault JM 《Applied microbiology and biotechnology》2005,68(3):316-321
An on-line technique, based on measuring the increase in pressure due to CO2 release in a closed air-tight reactor, was used to evaluate the fermentation of lactate by propionibacteria. The method was applied to batch cultures of Propionibacterium shermanii grown in yeast extract/sodium lactate medium containing lactate as a carbon source under micro-aerophilic conditions. Gas pressure evolution was compared both with substrate consumption and metabolites production and with acidification and growth. Linear relationships were found between gas pressure variation, lactate consumption and propionate and acetate production. The technique also enabled the evaluation of total CO2 produced, by taking account of pressure, oxygen and pH measurements. These results tend to show that this simple and rapid method could be useful to monitor propionic acid bacteria growth. 相似文献
4.
Nicholas Glanville Gary R. Mclean Bruno Guy Valerie Lecouturier Catherine Berry Yves Girerd Christophe Gregoire Ross P. Walton Rebecca M. Pearson Tatiana Kebadze Nicolas Burdin Nathan W. Bartlett Jeffrey W. Almond Sebastian L. Johnston 《PLoS pathogens》2013,9(9)
Human rhinovirus (RV) infections are the principle cause of common colds and precipitate asthma and COPD exacerbations. There is currently no RV vaccine, largely due to the existence of ∼150 strains. We aimed to define highly conserved areas of the RV proteome and test their usefulness as candidate antigens for a broadly cross-reactive vaccine, using a mouse infection model. Regions of the VP0 (VP4+VP2) capsid protein were identified as having high homology across RVs. Immunization with a recombinant VP0 combined with a Th1 promoting adjuvant induced systemic, antigen specific, cross-serotype, cellular and humoral immune responses. Similar cross-reactive responses were observed in the lungs of immunized mice after infection with heterologous RV strains. Immunization enhanced the generation of heterosubtypic neutralizing antibodies and lung memory T cells, and caused more rapid virus clearance. Conserved domains of the RV capsid therefore induce cross-reactive immune responses and represent candidates for a subunit RV vaccine. 相似文献
5.
Estelle Yaba Adje Rafik Balti Didier Lecouturier Mostafa Kouach Pascal Dhulster Didier Guillochon Naïma Nedjar-Arroume 《Probiotics and antimicrobial proteins》2013,5(3):176-186
The use of antimicrobial peptides (AMPs) is an alternative to traditional antibiotics. AMPs are obtained using different methods such as bacterial synthesis, chemical synthesis and controlled enzymatic hydrolysis. The later is an interesting approach that deserves our attention because of the yields gathered and peptides engineered. Usually, activities of AMPs obtained in such a way are tightly dependent on the hydrolysis mechanism used. This paper deals with the hydrolysis of hemoglobin mechanism as a potential source of AMPs. Production of AMPs from hemoglobin using enzymatic controlled system is linked to hemoglobin structure. Further, we show that bovine hemoglobin, which is sensitive to peptic hydrolysis, results upon enzymatic digestion as a great source of AMPs. The hemoglobin in native and denatured states was hydrolyzed by “one-by-one” and “zipper” mechanisms, respectively. Nevertheless, a new mechanism named “semi-zipper” mechanism is obtained when protein is in molten globule structural state, constituting an original strategy for AMPs production. Seventy seven percentage of the peptides obtained by this new strategy showed antibacterial activity against nine strains. 相似文献
6.
The dehalogenating performance of an anaerobic 5-amino-2,4,6-triiodoisophthalic acid (ATIA) fixed-bed reactor was evaluated. The reactor operating conditions were set for ATIA deiodination. A phylogenetic survey for a stable anaerobic ATIA-deiodinating microbial consortium was carried out using 16S rDNA restriction fragment length polymorphism, and unique clones were sequenced. Four phylotypes were identified. Two sequences were related to those of Desulfitobacterium frappieri species and another was closest to that of Desulfitobacterium hafniense, but may have represented a new Desulfitobacterium species. Desulfitobacteria were previously described as aryl-dechlorinating and debrominating bacteria. The new strains identified in this study were probably responsible for the ATIA deiodination. The fourth clone was related to the Clostridium-Flavobacterium-Bacteroides group. 相似文献
7.
François Coutte Didier Lecouturier Valérie Leclère Max Béchet Philippe Jacques Pascal Dhulster 《Process Biochemistry》2013,48(1):25-32
Recently, a bubbleless membrane bioreactor (BMBR) has been successfully developed for biosurfactant production by Bacillus subtilis [1]. In this study, for the first time, continuous culture were carried out for the production of surfactin in a BMBR, both with or without a coupled microfiltration membrane. Results from continuous culture showed that a significant part of biomass was immobilized onto the air/liquid membrane contactor. Immobilized biomass activity onto the air/liquid membrane contactor was monitored using a respirometric analysis. Kinetics of growth, surfactin and primary metabolites production were investigated. Planktonic biomass, immobilized biomass and surfactin production and productivity obtained in batch culture (3 L) of 1.5 days of culture were 4.5 g DW, 1.3 g DW, 1.8 g and 17.4 mg L?1 h?1, respectively. In continuous culture without total cell recycling (TCR), the planktonic biomass was leached, but immobilized biomass reached a steady state at an estimated 6.6 g DW. 11.5 g of surfactin was produced after 3 days of culture, this gave an average surfactin productivity of 54.7 mg L?1 h?1 for the continuous culture, which presented a surfactin productivity of 30 mg L?1 h?1 at the steady state. TCR was then investigated for the continuous production, extraction and purification of surfactin using a coupled ultrafiltration step. In continuous culture with TCR at a dilution rate of 0.1 h?1, planktonic biomass, immobilized biomass, surfactin production and productivity reached 7.5 g DW, 5.5 g DW, 7.1 g and 41.6 mg L?1 h?1 respectively, after 2 days of culture. After this time, biomass and surfactin productions stopped. Increasing dilution rate to 0.2 h?1 led to the resumption of biomass and surfactin production and these values reached 11.1 g DW, 10.5 g DW, 7.9 g and 110.1 mg L?1 h?1, respectively, after 3 days of culture. This study has therefore shown that with this new integrated bioprocess, it was possible to continuously extract and purify several grams of biosurfactant, with purity up to 95%. 相似文献
8.
Mathieu Vanhoute Renato Froidevaux Aurelien Vanvlassenbroeck Didier Lecouturier Pascal Dhulster Didier Guillochon 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2009,877(16-17):1683-1688
The ion-pair concept was applied on complex haemoglobin hydrolysates to extract two opioid peptides, LVV-haemorphin-7 and VV-haemorphin-7, in an aqueous/octan-1-ol micro-extraction system in the presence of alkyl-sulfonic acid as a surfactant agent and in relation to the haemorphin physico-chemical properties (charge, hydrophobicity). The effect of combined alkyl chain length/aqueous phase pH and the haem behaviour during the extraction, on the haemorphin recovery yield and enrichment has been determined. It has proved that transport over the organic phase is mediated by the alkyl-sulfonic acids, whatever be the aqueous phase pH. However, increasing both the alkyl chain length and the pH in the aqueous phase shows an haemorphin enrichment ratio increase but a recovery decrease of the extracted opioid peptides in the organic phase. Therefore, the best conditions to extract LVVh-7 and VVh-7 are the use of the octane-sulfonic acid at aqueous phase pH of 5 or 7 and the octane or the heptane-sulfonic acid with an aqueous phase pH of 5 or 7 respectively. In these conditions, a partition coefficient of 1.64 and 1.60 respectively for LVVh-7 and VVh-7 are obtained and represent about 40 times that acquired without agent. 相似文献
9.
F. Coutte V. Leclère M. Béchet J.‐S. Guez D. Lecouturier M. Chollet‐Imbert P. Dhulster P. Jacques 《Journal of applied microbiology》2010,109(2):480-491
Aims: To analyse the effects of plipastatin operon disruption and constitutive expression of surfactin operon in Bacillus subtilis 168 on surfactin productivity, in vitro invasive growth and antagonism against fungi. Methods and Results: The srfA native promoter was replaced by the constitutive promoter PrepU in B. subtilis 168 after integration of a functional sfp gene. Moreover, the plipastatin synthesis was further disrupted in the B. subtilis 168 derivatives. In liquid media, an earlier and higher expression of PrepU, than that found with PsrfA, led to a specific surfactin production fivefold higher after 6 h of culture. On solid media, not only the invasive growth and the haemolytic activity but also the antifungal activity of the constitutive strains were improved when compared to the parental strain BBG111. As expected, the disruption of the plipastatin operon strongly reduced in vitro antifungal properties but, interestingly, enhanced specific surfactin production (1·47 g g?1 of biomass), spreading behaviour and haemolytic activity of the strains. Conclusions: This work demonstrates for the first time the interdependency of surfactin and plipastatin regarding their biosynthesis as well as their influence on the biological activities of the producing strain. Significance and Impact of the Study: The constitutive overproduction of surfactin enhances the invasive growth and the in vitro antagonistic activity of the mutant strain. Both properties are known to play an important role in the biocontrol of plant diseases. Plipastatin operon disruption increases the surfactin productivity of mutant strains. These mutants are interesting for use in continuous bioprocesses for surfactin production or in bioremediation. 相似文献
10.
François Coutte Didier Lecouturier Saliha Ait Yahia Valérie Leclère Max Béchet Philippe Jacques Pascal Dhulster 《Applied microbiology and biotechnology》2010,87(2):499-507
Surfactin and fengycin are lipopeptide biosurfactants produced by Bacillus subtilis. This work describes for the first time the use of bubbleless bioreactors for the production of these lipopeptides by B. subtilis ATCC 21332 with aeration by a hollow fiber membrane air–liquid contactor to prevent foam formation. Three different configurations
were tested: external aeration module made from either polyethersulfone (reactor BB1) or polypropylene (reactor BB2) and a
submerged module in polypropylene (reactor BB3). Bacterial growth, glucose consumption, lipopeptide production, and oxygen
uptake rate were monitored during the culture in the bioreactors. For all the tested membranes, the bioreactors were of satisfactory
bacterial growth and lipopeptide production. In the three configurations, surfactin production related to the culture volume
was in the same range: 242, 230, and 188 mg l−1 for BB1, BB2, and BB3, respectively. Interestingly, high differences were observed for fengycin production: 47 mg l−1 for BB1, 207 mg l−1 for BB2, and 393 mg l−1 for BB3. A significant proportion of surfactin was adsorbed on the membranes and reduced the volumetric oxygen mass transfer
coefficient. The degree of adsorption depended on both the material and the structure of the membrane and was higher with
the submerged polypropylene membrane. 相似文献