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991.
Chami M Andréau K Lemassu A Petit JF Houssin C Puech V Bayan N Chaby R Daffé M 《FEMS immunology and medical microbiology》2002,32(2):141-147
Vesicles consisting of pure trehalose dicorynomycolate (TDCM), the corynebacterial analog of the most studied mycobacterial glycolipid 'cord factor', were isolated from Corynebacterium glutamicum cells by mild detergent treatment; these induced in vivo a macrophage priming similar to that obtained with mycobacterial-derived trehalose dimycolate. In vitro, both TDCM and bacterial lipopolysaccharide (LPS) induced in macrophages the production of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha), endotoxin tolerance, and were primed for an enhanced secondary NO response to LPS. Interferon-gamma pretreatment did not influence the LPS-induced TNF-alpha response, but considerably increased the TDCM-induced response. 相似文献
992.
Expression of chitin deacetylase from Colletotrichum lindemuthianum in Pichia pastoris: purification and characterization 总被引:4,自引:0,他引:4
The chitin deacetylase gene from Colletotrichum lindemuthianum UPS9 was isolated and cloned in Pichia pastoris as a tagged protein with six added terminal histidine residues. The expressed enzyme was recovered from the culture supernatant and further characterized. A single-step purification based on specific binding of the histidine residues was achieved. The purified enzyme has a molecular mass of 25 kDa and is not glycosylated as determined by mass spectrometry. The activity of the recombinant chitin deacetylase on chitinous substrates was investigated. With chitotetraose as substrate, the optimum temperature and pH for enzyme activity are 60 degrees C and 8.0, respectively. The specific activity of the pure protein is 72 U/mg. One unit of enzyme activity is defined as the amount of enzyme that produces 1 micromol of acetate per minute under the assay conditions employed. The enzyme activity is enhanced in the presence of Co2+ ions. A possible use of the recombinant chitin deacetylase for large-scale biocatalytic conversion of chitin to chitosan is discussed. 相似文献
993.
The neuronal growth cone provides the sensory and motor structure that guides neuronal processes to their target. The ability of a growth cone to navigate correctly depends on its filopodia, which sample the environment by continually extending and retracting as the growth cone advances. Several second messengers systems that are activated upon contact with extracellular cues have been reported to affect growth cone morphology by changing the length and number of filopodia. Because recent studies have suggested that guidance cues can signal via G-protein coupled receptors to regulate phospholipases, we here investigated whether phospholipase A2 (PLA2) may control filopodial dynamics and could thereby affect neuronal pathfinding. Employing identified Helisoma neurons in vitro, we demonstrate that inhibition of PLA2 with 2 microM BPB caused a 40.3% increase in average filopodial length, as well as a 37.3% reduction in the number of filopodia on a growth cone. The effect of PLA2 inhibition on filopodial length was mimicked by the inhibition of G-proteins with 500 ng/ml pertussis toxin and was partially blocked by the simultaneous activation of PLA2 with 50 nM melittin. We provide evidence that PLA2 acts via production of arachidonic acid (AA), because (1) the effect of inhibition of PLA2 could be counteracted by supplying AA exogenously, and (2) the inhibition of cyclooxygenase, which metabolizes AA into prostaglandins, also increased filopodial length. We conclude that filopodial contact with extracellular signals that alter the activity of PLA2 can control growth cone morphology and may affect neuronal pathfinding by regulating the sensory radius of navigating growth cones. 相似文献
994.
Trésaugues L Collinet B Minard P Henckes G Aufrère R Blondeau K Liger D Zhou CZ Janin J Van Tilbeurgh H Quevillon-Cheruel S 《Journal of structural and functional genomics》2004,5(3):195-204
The South-Paris Yeast Structural Genomics Project aims at systematically expressing, purifying and determining the structure of S. cerevisiae proteins with no detectable homology to proteins of known structure. We brought 250 yeast ORFs to expression in E. coli, but 37% of them form inclusion bodies. This important fraction of proteins that are well expressed but lost for structural studies prompted us to test methodologies to recover these proteins. Three different strategies were explored in parallel on a set of 20 proteins: (1) refolding from solubilized inclusion bodies using an original and fast 96-well plates screening test, (2) co-expression of the targets in E. coli with DnaK-DnaJ-GrpE and GroEL-GroES chaperones, and (3) use of the cell-free expression system. Most of the tested proteins (17/20) could be resolubilized at least by one approach, but the subsequent purification proved to be difficult for most of them. 相似文献
995.
996.
The sigma(54) subunit of the RNA polymerase directs the expression of specific operons in association with cognate activators. Three different activators have been detected in the Listeria monocytogenes genome on the basis of the high conservation of a specific domain. Among them, the LacR activator, of the LevR family, was found just upstream from a newly described sigma(54)-dependent operon, lpo, which presents a classical -24/-12 consensus promoter. The lpo operon encodes proteins similar to subunits of a PTS permease (EII) of the lactose family, namely LpoA (IIA) and LpoB (IIB). It also encodes a third putative protein, LpoO, with an unknown function but sharing high similarity with proteins also encoded within PTS operons from other bacteria and bearing a RGD motif. The expression of lpo was clearly dependent on LacR and sigma(54), and was induced by cellobiose, chitobiose and lactose. It underlies that the lpo operon likely encodes proteins involved in the utilization of these sugars by L. monocytogenes. 相似文献
997.
Gautier-Bert K Murol B Jarrousse AS Ballut L Badaoui S Petit F Schmid HP 《Molecular biology reports》2003,30(1):1-7
We have partially reconstituted 20S proteasome/RNA complexes using oligonucleotides corresponding to ARE (adenosine- and uridine-rich element) (AUUUA)4 and HIV-TAR (human immunodeficiency virus-Tat transactivation response element), a stem-loop structure in the 5 UTR (untranslated region) of HIV-mRNAs. We demonstrate that these RNAs which associate with proteasomes are degraded by proteasomal endonuclease activity. The formation of these 20S proteasome/RNA substrate complexes is rather specific since 20S proteasomes do not interfere with truncated TAR that is not cleaved by proteasomal endonuclease. In addition, affinity of proteasomes for (AUUUA)4 is much stronger as it is for HIV-TAR. These results provide further arguments for our hypothesis that proteasomes could be involved in the destabilisation of cytokines mRNAs containing AUUUA sequences as well as viral mRNAs. 相似文献
998.
The SWISS-PROT protein knowledgebase and its supplement TrEMBL in 2003 总被引:56,自引:4,他引:52
Boeckmann B Bairoch A Apweiler R Blatter MC Estreicher A Gasteiger E Martin MJ Michoud K O'Donovan C Phan I Pilbout S Schneider M 《Nucleic acids research》2003,31(1):365-370
The SWISS-PROT protein knowledgebase (http://www.expasy.org/sprot/ and http://www.ebi.ac.uk/swissprot/) connects amino acid sequences with the current knowledge in the Life Sciences. Each protein entry provides an interdisciplinary overview of relevant information by bringing together experimental results, computed features and sometimes even contradictory conclusions. Detailed expertise that goes beyond the scope of SWISS-PROT is made available via direct links to specialised databases. SWISS-PROT provides annotated entries for all species, but concentrates on the annotation of entries from human (the HPI project) and other model organisms to ensure the presence of high quality annotation for representative members of all protein families. Part of the annotation can be transferred to other family members, as is already done for microbes by the High-quality Automated and Manual Annotation of microbial Proteomes (HAMAP) project. Protein families and groups of proteins are regularly reviewed to keep up with current scientific findings. Complementarily, TrEMBL strives to comprise all protein sequences that are not yet represented in SWISS-PROT, by incorporating a perpetually increasing level of mostly automated annotation. Researchers are welcome to contribute their knowledge to the scientific community by submitting relevant findings to SWISS-PROT at swiss-prot@expasy.org. 相似文献
999.
1000.