The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Marc J.s. De Wolf - One of the best experts on this subject based on the ideXlab platform.
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Vibrio Cholerae: Cholera Toxin
The International Journal of Biochemistry & Cell Biology, 2007Co-Authors: Davy Vanden Broeck, Caroline A.j. Horvath, Marc J.s. De WolfAbstract:Abstract The bacterial protein Toxin of Vibrio Cholerae , Cholera Toxin, is a major agent involved in severe diarrhoeal disease. Cholera Toxin is a member of the AB Toxin family and is composed of a catalytically active heterodimeric A-subunit linked with a homopentameric B-subunit. Upon binding to its receptor, GM0 1 , Cholera Toxin is internalized and transported in a retrograde manner through the Golgi to the ER, where it is retrotranslocated to the cytosol. Here, Cholera Toxin reaches its intracellular target, the basolaterally located adenylate cyclase which becomes constitutively activated after Toxin-induced mono-ADP-ribosylation of the regulating G S -protein. Elevated intracellular cAMP levels provoke loss of water and electrolytes which is manifested as the typical diarrhoea. The Cholera Toxin B-subunit displays the capacity to fortify immune responses to certain antigens, to act as a carrier and to be competent in inducing immunological tolerance. These unique features make Cholera Toxin a promising tool for immunologists.
Davy Vanden Broeck - One of the best experts on this subject based on the ideXlab platform.
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Vibrio Cholerae: Cholera Toxin
The International Journal of Biochemistry & Cell Biology, 2007Co-Authors: Davy Vanden Broeck, Caroline A.j. Horvath, Marc J.s. De WolfAbstract:Abstract The bacterial protein Toxin of Vibrio Cholerae , Cholera Toxin, is a major agent involved in severe diarrhoeal disease. Cholera Toxin is a member of the AB Toxin family and is composed of a catalytically active heterodimeric A-subunit linked with a homopentameric B-subunit. Upon binding to its receptor, GM0 1 , Cholera Toxin is internalized and transported in a retrograde manner through the Golgi to the ER, where it is retrotranslocated to the cytosol. Here, Cholera Toxin reaches its intracellular target, the basolaterally located adenylate cyclase which becomes constitutively activated after Toxin-induced mono-ADP-ribosylation of the regulating G S -protein. Elevated intracellular cAMP levels provoke loss of water and electrolytes which is manifested as the typical diarrhoea. The Cholera Toxin B-subunit displays the capacity to fortify immune responses to certain antigens, to act as a carrier and to be competent in inducing immunological tolerance. These unique features make Cholera Toxin a promising tool for immunologists.
J. Holmgren - One of the best experts on this subject based on the ideXlab platform.
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Cholera Toxin structure, gene regulation and pathophysiological and immunological aspects
Cellular and Molecular Life Sciences, 2008Co-Authors: J. Sánchez, J. HolmgrenAbstract:Many notions regarding the function, structure and regulation of Cholera Toxin expression have remained essentially unaltered in the last 15 years. At the same time, recent findings have generated additional perspectives. For example, the Cholera Toxin genes are now known to be carried by a non-lytic bacteriophage, a previously unsuspected condition. Understanding of how the expression of Cholera Toxin genes is controlled by the bacterium at the molecular level has advanced significantly and relationships with cell-density-associated (quorum-sensing) responses have recently been discovered. Regarding the cell intoxication process, the mode of entry and intracellular transport of Cholera Toxin are becoming clearer. In the immunological field, the strong oral immunogenicity of the non-toxic B subunit of Cholera Toxin (CTB) has been exploited in the development of a now widely licensed oral Cholera vaccine. Additionally, CTB has been shown to induce tolerance against co-administered (linked) foreign antigens in some autoimmune and allergic diseases.
Caroline A.j. Horvath - One of the best experts on this subject based on the ideXlab platform.
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Vibrio Cholerae: Cholera Toxin
The International Journal of Biochemistry & Cell Biology, 2007Co-Authors: Davy Vanden Broeck, Caroline A.j. Horvath, Marc J.s. De WolfAbstract:Abstract The bacterial protein Toxin of Vibrio Cholerae , Cholera Toxin, is a major agent involved in severe diarrhoeal disease. Cholera Toxin is a member of the AB Toxin family and is composed of a catalytically active heterodimeric A-subunit linked with a homopentameric B-subunit. Upon binding to its receptor, GM0 1 , Cholera Toxin is internalized and transported in a retrograde manner through the Golgi to the ER, where it is retrotranslocated to the cytosol. Here, Cholera Toxin reaches its intracellular target, the basolaterally located adenylate cyclase which becomes constitutively activated after Toxin-induced mono-ADP-ribosylation of the regulating G S -protein. Elevated intracellular cAMP levels provoke loss of water and electrolytes which is manifested as the typical diarrhoea. The Cholera Toxin B-subunit displays the capacity to fortify immune responses to certain antigens, to act as a carrier and to be competent in inducing immunological tolerance. These unique features make Cholera Toxin a promising tool for immunologists.
Shi C - One of the best experts on this subject based on the ideXlab platform.
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A promoter responsible for over-expression of Cholera Toxin B subunit in Cholera Toxin A subunit structure gene
Yi chuan xue bao = Acta genetica Sinica, 1997Co-Authors: Cheng Cao, Shi CAbstract:A promoter sequence, which promotes the transcription of Cholera Toxin B subunit gene, was found in Cholera Toxin A subunit structure gene. The transcription starts at the adenine Located at +833, that is 456bp upstream to the A of the initiation codon ATG of Cholera Toxin B gene. Under the control of the promoter, Cholera Toxin B subunit was over-expressed as high as 200 mg/L at an optimized culture condition. The chloramphenicol acetyl transferase gene and beta-galactosidase could also be efficiently expressed under the direction of the promoter. This promoter may be responsible for the 6 fold and 7 fold higher expression level of Cholera Toxin B subunit than Cholera Toxin A subunit in V. Cholerae and Escheria coli respectively. The over-expression of CTB may be useful in preparing vaccine against Cholera and facilitating the construction of peptide-bearing immunogenic hybrid proteins.
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The upstream sequence of Cholera Toxin B subunit gene: effect on CTB expression
Yi chuan xue bao = Acta genetica Sinica, 1994Co-Authors: Cheng Cao, Shi CAbstract:In this work, we have studied the effect of Cholera Toxin A structure gene on the expression of the distal ctxB gene by the methods of deletion and frame-shift mutation. The results showed that: The expression level of Plasmid pUC19CTB, which was constructed by cloning the XbaI-EcoRI restriction fragment into pUC19 and ctxA gene was out-frame with lacZ' gene, is about 30 micrograms/ml; If a frame shift mutation was introduced at XbaI site of pUC19CTB so that the Cholera Toxin A gene was inframe with lacZ' and could be translated, the expression level of ctxB was decreased to 12 micrograms/ml; When A further deletion from XbaI to ClaI of Cholera Toxin A gene (about 550bp) was made and ctxA was outframe with LacZ', ctxB expression was decreased two fold compared to pUC19CTB; If the ctxA was inframe with LacZ' so ctxA gene could be translated, the expression level of CTB is much lower than the plasmid outframe with lacZ'. These observations could not be explained by the current knowledge about genetical regulation of Cholera Toxin operon. The promoter we found located in the Cholera Toxin A subunit gene, which is responsible for the expression of Cholera Toxin B subunit, may answer the question why the 550bp non-coding sequence could enhance the expression of Cholera Toxin B subunit.