Neuraminidase is produced by cholera cells as an invasion, neuraminidase is part of a group of enzymes responsible for removing the carbohydrate sialic acid. The gastrointestinal (GI) tract is coated with a mucus lining with the aim to prevent pathogens such as CT from entering the endothelial cells of the gut lining. , where, in an effort to infect cells, the bacterium V. The location of CTX’s function is found in the lumen of the small intestine. The alpha subunit is cleaved apart once inside the cell via trypsin which breaks the disulphide bonds between A1 and A2, allowing the A1 chain to dissociate and begin its catalytic activity, leaving the A2 domain which had been anchoring the A1 chain to the Beta subunit. A2 is an extended alpha helix, connecting the alpha subunit to the Beta subunit. A1 is enzymatic and does most of the work, once inside the cell. The A subunit which is located at the centre of the toxin whilst the five beta subunits are arranged into a pentameric ring and are responsible for binding the toxin to a cell's membrane, weighing 11 kDa each and are made from a chain of 103 amino acids, binds to five ganglioside GM1 receptors on the plasma membrane and triggers endocytosis of the toxin, whilst the Alpha subunit is made up of an A1 and A2 chain, the alpha subunit is made up of a chain of 240 amino acids. ĬT is a member of the AB5 family of toxins and consists of subunits, one Alpha polypeptide and five Beta polypetides that are associated via noncovalent bonds. CT, once secreted into a system, initiates its toxic action by means of binding to high-affinity cell membrane receptors identified to be the ganglioside or GM1 receptors. cholerae secretes the enterotoxin CT in a very efficient manner with more than 90% of the toxin found extracellularly. cholerae enters its human host, the bacterium propels themselves through the mucous membranes of the ileum attaching themselves to the epithelial lining releasing CT thus activating a cascade of cell signalling pathways leading to massive fluid loss from the ileum and duodenum. cholerae, known to lie dormant in water and food supplies that have been contaminated by human excrement is a concern for large-scale outbreaks. cholerae is a comma-shaped, gram-negative bacterium and has one flagellum at the positioned at the pole of the cell. In extreme circumstances cholera can lead to death. CT is characterised by its ability to cause severe diarrhoea, often leading to dehydration. The toxin activates the chloride channel proteins to open and allow the movement of chloride ions out of the cell in the absence of the signalling molecule. The cholera toxin affects the epithelial cells in the intestine by interfering with the cells signalling pathway, the toxin causes overactivation of the signalling pathway that controls the activity of chloride channel proteins.
CT is transmitted between patients via the faecal-oral route, therefore, is often found in countries with poor sanitation. CT is the cause of cholera, often from dirty water. Cholera Toxin (CT or CTX) is a protein enterotoxin, secreted by toxic species of the bacterium Vibrio cholerae.
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