Enterotoxin proteins

Rotavirus enterotoxin protein NSP4 fused to CTB Potato Fusion proteins assembled into cholera holo-toxin-like structures that retained enterocyte-binding affinity Orally immunized mice generated levels of serum and mucosal antibodies specific for the native antigen. Induced TH1 immune response. 63,64... 

Figure 8. A current record of asolectin bilayer which incorporated the enterotoxin protein. Holding potential + 11.5 mV.

V. cholerae is a gram-negative bacillus. Vibrios pass through the stomach to colonize the upper small intestine. Vibrios have filamentous protein extensions that attach to receptors on the intestinal mucosa, and their motility assists with penetration of the mucus layer.2 The cholera enterotoxin consists of two subunits, one of which (subunit A) is transported into the cells and causes an increase in cyclic AMP, which leads to a deluge of fluid into the small intestine.20 This large volume of fluid results in the watery diarrhea that is characteristic of cholera. The stools are an electrolyte-rich isotonic fluid, the loss of which results in blood volume depletion followed by low blood pressure and shock.2 Of note, the diarrheal fluid is highly infectious. 

Toxins (typically high molecular weight proteins), such as botulinum toxin, ricin, or Staphyloccocal enterotoxin (SEB) or T-2 toxin (which actually is a small molecule). 

Just I, Wilm M, Selzer J, Rex G, von Eichel-Streiber C, Mann M, Aktories K The enterotoxin from Clostridium difficile (ToxA) mono-glucosylates the Rho proteins. J Biol Chem 1995 270 13932-13936. 

Antibiotics alter the normal colonic flora, leading to loss of colonization resistance, which is the ability of the normal flora to protect against overgrowth of pathogens, especially when the anaerobic flora are depleted [15], In CDAD, the altered colonization resistance can allow for the overgrowth of C. difficile in the colon. The bacteria produces two toxins which cause disease (toxin A, an enterotoxin, and toxin B, a cytotoxin). The toxins of C. difficile inactivate Rho proteins, which results in the loss of cytoskeletal integrity in enterocytes. Cellular damage results in fluid loss, exudation and diarrhea. The most severe form of C. difficile diarrhea is pseudomembranous colitis, which can cause severe colitis, toxic colon and rarely colon perforation and death. 

Protein toxins such as botulism, staphylococcal enterotoxin B, or ricin can be separated with gas or liquid chromatography, electrophoresis, or a combination. The pChemLab (Sandia National Laboratories Albuquerque, NM) series of instruments includes a hand-held Bio Detector. Proteins in the sample are labeled with fluorescent tags, and nanoliter volumes of samples are separated by microchannels etched into a glass chip. The separation occurs as the sample moves through the channels and identification is based on retention times. The analyses can be completed within 10 min. 

The addition of soy protein likewise did not enhance the production of enterotoxin by Staphylococcus aureus 5-6 (33). However, the addition of soy protein did increase the pH of the resultant product from 5.8-5.9 to 6.1 and resulted in a significant increase in D-values of salmonellae at 54 and 60°C (34). 

S. R. Monday G. A. Bohach, Properties ot Staphylococcus aureus Enterotoxins and Toxic Shock Syndrome Toxin-1. in The Comprehensive Sourcebook of Bacterial Protein Toxins, 2nd ed. J. E. Aiout, J. H. Freer, Eds. Academic Press London, 1999 pp 589-610. 

Yersinia enterocolitica Proliferation in gut associated lymphoid tissue (facultative intracellular pathogen)(heat stable enterotoxin, LPS, invasin, attachment/invasion protein adhesion Ail) Bacillus cereus Emetic toxin (vomiting) Enterotoxins (diarrheal illness) ... 

There are a large number of proteins that share this designation. Perhaps the best known is the heat-labile enterotoxin from E. coli that catalyzes the ADP-ribosyla-tion of a number of proteins. 

In 1990, the first plant-made vaccines were performed via expression of Streptococcus mutans surface protein A in transgenic tobacco, followed by oral immunization of mice with the same plant material (Fischer and Emans, 2000). This transgenic plant material was later shown to successfully induce an antibody response through a demonstration that serum from immunized mice could react with intact S. mutans. Plants were also developed that expressed Escherichia coli enterotoxin B subunit (LT-B) and that exhibited successful inducement of both mucosal and serum antibody responses (Tacket, 2005). These initial experiments led to a cornucopia of studies involving generations of plant-made vaccines and therapeutic proteins and their applications in medicine. 

This bimodal dynamics of hydration water is intriguing. A model based on dynamic equilibrium between quasi-bound and free water molecules on the surface of biomolecules (or self-assembly) predicts that the orientational relaxation at a macromolecular surface should indeed be biexponential, with a fast time component (few ps) nearly equal to that of the free water while the long time component is equal to the inverse of the rate of bound to free transition [4], In order to gain an in depth understanding of hydration dynamics, we have carried out detailed atomistic molecular dynamics (MD) simulation studies of water dynamics at the surface of an anionic micelle of cesium perfluorooctanoate (CsPFO), a cationic micelle of cetyl trimethy-lainmonium bromide (CTAB), and also at the surface of a small protein (enterotoxin) using classical, non-polarizable force fields. In particular we have studied the hydrogen bond lifetime dynamics, rotational and dielectric relaxation, translational diffusion and vibrational dynamics of the surface water molecules. In this article we discuss the water dynamics at the surface of CsPFO and of enterotoxin. 

WATER DYNAMICS AT THE SURFACE OF A SMALL PROTEIN, ENTEROTOXIN... 

The protein that we study here is the toxic domain of heat stable Enterotoxin (PDB ID lETN). Heat stable Enterotoxins (ST) are produced by E. Coli bacteria in the intestine and are responsible for acute diarrhea in humans and animals. They display a remarkable ability... 

Shimonishi and coworkers observed that the residues in the second P turn are proximal to the receptor in the binding of enterotoxin [12]. This ties in with the observation that the toxicity of the protein too is unaffected by changing specific residues in the first and the third / turns, while the activity was considerably affected when similar mutations were effected in the residues of the second /3 turn. In order to relate to these biochemical studies, we have classified the hydration layer of 1ETN into three regions, based on their proximity to each of the three 6 turns. 

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