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41.
Induction of phagocytic behaviour in human epithelial cells by Escherichia coli cytotoxic necrotizing factor type1 总被引:7,自引:0,他引:7
Loredana Falzano Carla Fiorentini Gianfranco Donelli Eric Michel Christine Kocks Pascale Cossart Lucien Cabanié Eric Oswald Patrice Boquet 《Molecular microbiology》1993,9(6):1247-1254
Cytotoxic necrotizing factor type 1 (CNF1) from strains of pathogenic Escherichia coli induces in human epithelial HEp-2 cells, a profound reorganization of the actin cytoskeleton into prominent stress fibres and membrane ruffles. We report here that this process is associated with induction of phagocytic-like activity. CNF1-treated cells acquired the ability to ingest latex beads as well as non-invasive bacteria such as Listeria innocua, which were taken as a model system. Uptake of bacteria was similar to pathogen-induced phagocytosis, since L. innocua transformed with DNA coding for the pore-forming toxin listeriolysln O behaved, with respect to intracellular growth, like the invasive, pathogenic species L. monocytogenes. Our results raise the possibility that, in vivo, pathogenic CNF1 -producing E. coli may invade epithelia by this novel induced phagocytic-like mechanism. 相似文献
42.
Bruno Mhul Michle Aubery Hans-Georg Mannherz Patrice Codogno 《Journal of cellular biochemistry》1993,52(3):266-274
The myoblast cell surface activity of ecto-5′-nucleotidase was stimulated by a laminin substrate, whereas fibronectin and gelatin did not increase the AMPase activity of ecto-5′-nucleotidase. This increase was related to a higher expression of ecto-5′-nucleotidase on the surface of cells seeded on a laminin substrate, but without the mobilization of an intracellular pool of enzyme. Furthermore, laminin and its fragments E′1 and E8 modified the AMPase activity of the ecto-5′-nucleotidase purified from chicken striated muscle and reconstituted in liposomes. Over the range of concentrations used, intact laminin and its fragment E8, consisting of the distal half of the long arm, stimulated the AMPase activity of ecto-5′-nucleotidase. By contrast, the large fragment derived from the short arms, designated E′1, inhibited the AMPase activity. Furthermore, the monoclonal anti-ecto-5′-nucleotidase antibody, CG37, abolished the stimulatory effect of fragment E8 on the AMPase activity of ecto-5′-nucleotidase but did not reverse the inhibitory effect of fragment E′1. In conclusion, laminin stimulates the AMPase activity of ecto-5′-nucleotidase by two mechanisms: inducing the expression of ecto-5′-nucleotidase to the cell surface and direct modulation of the enzymatic activity. 相似文献
43.
Bruno Kieffer Patrice Koehl Serge Plaue Jean-François Lefèvre 《Journal of biomolecular NMR》1993,3(1):91-112
Summary We have investigated the dynamics and structural behaviour of two antigenic peptides using 1H NMR. The two cyclic peptides mimic the antigenic site A of influenza haemagglutinin protein; they only differ in the way they were cyclized and in the size of their respective linkers. Homonuclear relaxation parameters extracted from a complete NOE matrix were interpreted in terms of local dynamics. A set of distance constraints was deduced from these parameters which allowed 3D models to be constructed using distance geometry. NOE back-calculation was used to check the validity of the final models. Strong variations of internal motion amplitude have been found in both peptides along their backbone. Motions with high amplitudes have been localized in the Gly-Pro-Gly sequence which forms a -turn in both structures.Abbreviations DSS
3-(trimethylsilyl)-1-propanesulfonic acid
- D-loop
aspartic acid loop
- ELISA
enzyme-linked immunoabsorbent assay
- f.i.d
free induction decay
- HOHAHA
homonuclear Hartmann-Hahn spectroscopy
- HPLC
high pressure liquid chromatography
- K-loop
lysine loop
- NMR
nuclear magnetic resonance
- NOE
nuclear Overhauser enhancement
- NOESY
nuclear Overhauser enhancement spectroscopy
- r.m.s.d.
root-mean-square deviation of atomic positions 相似文献
44.
Sabine Lhernould Yannis Karamanos Patrice Lerouge Henri Morvan 《Glycoconjugate journal》1995,12(1):94-98
The peptide-N
4-(N-acetylglucosaminyl) asparagine amidase (PNGase Se) earlier described [Lhernould S., Karamanos Y., Bourgerie S., Strecker G., Julien R., Morvan H. (1992)Glycoconjugate J
9:191–97] was partially purified from culturedSilene alba cells using affinity chromatography. The enzyme is active between pH 3.0 and 6.5, and is stable in the presence of moderate concentrations of several other protein unfolding chemicals, but is readily inactivated by SDS. Although the enzyme cleaves the carbohydrate from a variety of animal and plant glycopeptides, it does not hydrolyse the carbohydrate from most of the corresponding unfolded glycoproteins in otherwise comparable conditions. The substrate specificity of this plant PNGase supports the hypothesis that this enzyme could be at the origin of the production of unconjugated N-glycans in a suspension medium of culturedSilene alba cells.Abbreviations GlcNAc
N-acetylglucosamine
- PNGase
peptide-N
4-(N-acetylglucosaminyl) asparagine amidase
- BSA
bovine serum albumin
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- TLC
thin layer chromatography
- HPAEC-PAD
High pH anion exchange chromatography-pulsed amperometric detection 相似文献
45.
Sujoy Ghosh John W. Kyle Sara Dastgheib Francois Daussin Zhixiong Li Subhash Basu 《Glycoconjugate journal》1995,12(6):838-847
A 1-3 galactosyltransferase (GalT-3; UDP-Gal; GM2 1-3galactosyltransferase) was purified over 5100-fold from 19-day-old embryonic chicken brain homogenate employing detergent solubilization, -lactalbumin Sepharose, Q-Sepharose, UDP-hexanolamine Sepharose, and GalNAc1-4Gal-Synsorb column chromatography. The purified enzyme was resolved into two bands on reducing gels with apparent molecular weights of 62 kDa and 65 kDa, respectively. GalT-3 activity was also localized in the same regions by activity gel analysis and sucrose-density gradient centrifugation of a detergent-solubilized extract of 19-day-old embryonic chicken brain. Purified GalT-3 exhibited apparentK
mS of 33 µm, 22 µm and 14.4mM with respect to the substrates GM2, UDP-galactose, and MnCl2, respectively. Substrate specificity studies with the purified enzyme and a variety of glycosphingolipids, glycoproteins, and synthetic substrates revealed that the enzyme was highly specific only for the glycosphingolipid acceptors, GM2 and GgOse3Cer (asialo-GM2). Ovine-asialo-agalacto submaxillary mucin inhibited the transfer of galactose to GM2 but did not act as an acceptor in the range of concentrations tested. Polyclonal antibodies raised against purified GalT-3 inhibited GalT-3 activityin vitro and Western-immunoblot analysis of purified GalT-3 showed immunopositive bands at 62 and 65 kDa.Abbreviations CNS
central nervous system
- GM1
monosialotetraosylganglioside, Gal1-3GalNAc1-4(NeuAc2-3)Gal1-4Glc1-1Cer
- GM2
monosialotriaosylganglioside, GalNAc1-4(NeuAc2-3)Gal1-4Glc1-1Cer
- DSS
detergent solubilized supernatant
- ECB
embryonic chicken brain
- TBS
Tris-buffered saline 相似文献
46.
Suzanne Demczuk Annie Lévy Muriel Aubry Marie-Françoise Croquette Nicole Philip Marguerite Prieur Ursula Sauer Patrice Bouvagnet Guy A. Rouleau Gilles Thomas Alain Aurias 《Human genetics》1995,96(1):9-13
We have determined the parental origin of the deleted chromosome 22 in 29 cases of DiGeorge syndrome (DGS) using a CA-repeat mapping within the commonly deleted region, and in one other case by using a chromosome 22 short arm heteromorphism. The CA-repeat was informative in 21 out of 29 families studied and the deleted chromosome was of maternal origin in 16 cases (72%). When these data are pooled with recent results from the literature, 24 de novo DGS, velo-cardio-facial syndrome (VCFS) and isolated conotruncal cardiac disease deletions are found to be of maternal origin and 8 of paternal origin, yielding a 2 of 8 with a probability level lower than 0.01. These data, and review of the literature on familial DGS/VCFS and isolated conotruncal cardiopathies suggest that there is a strong tendency for the 22q11.2 deletions to be of maternal origin. 相似文献
47.
48.
We have determined the complete nucleotide sequence of the right (R) copy of the insertion sequence IS15 which flanks, in direct orientation, the composite transposon Tn1525. IS15-R, which is capable of independent transposition, is 1648 bp long and has short (14 bp) perfect inverted repeats at its termini. Analysis of the nucleotide sequence indicates that IS15-R results from the transposition, in direct orientation, of a smaller (820 bp long) IS, designated IS15-Δ, into itself. This integration event is accompanied by the duplication of 8 bp in the target DNA. IS15-Δ possesses two large overlapping open reading frames (ORF) located on opposite strands. Because of this particular structure, IS15 possesses four large ORFs which, due to the integration event, exhibit some differences with those of the parental 1S15-Δ. 相似文献
49.
Patrice Allibert J.Martin Odom J.D. Wall P.M. Vignais 《FEMS microbiology letters》1984,23(2-3):221-226
Abstract Spontaneous nitrogenase-negative (Nif− mutants of Rhodopseudomonas capsulata were observed to accumulate with time in ammonium- or glutamate-limited chemostat cultures.
Nif− mutants were characterized by their inability to grow under N2 and to reduce acetylene or produce hydrogen gas when grown on glutamate. They lacked the nitrogenase structural proteins as evidenced by immunological techniques. On the other hand, no significant differences were found in the pathways of ammonia assimilation between the Nif− mutants and the wild-type strain. The Nif− mutants seem to result from a mutation in a regulatory gene. 相似文献
Nif
50.
Francois Raulin 《Origins of life and evolution of the biosphere》1980,10(4):371-377
A conference on Life in the Universe, organized by the Council of Europe, and held in Paris, November 19 to 21, 1979, brought together more than 100 scientists from different fields. The aim of this conference was to promote scientific cooperation in Europe, in conjunction with other countries, in fields related to the problem of Life in the Universe. Our knowledge concerning this problem was reviewed in three different sessions. The first session was devoted to the question of planetary evolution; the second session was devoted to the question of the origin and evolution of life, and the third session was devoted to the problem of evolution of intelligence and the search for extraterrestrial intelligence. The Drake formula was the keynote of the conference. Each session tried to estimate some of the parameters of this formula, in order to examine the question: how many extraterrestrial civilizations with a level of technology at least equal to ours may be present in the universe? Even if no definite answer is given to this question, this meeting pointed out the need for more research. 相似文献