Bacterial toxins, binding

Moran-Mirabal JM, Edel JB, Meyer GD et al (2005) Micrometer-sized supported lipid bilayer arrays for bacterial toxin binding studies through total internal reflection fluorescence microscopy. Biophys J 89 296-305... 

Heterotrimeric GTP-binding Proteins Small GTPases Bacterial Toxins... 

It has the ability to cross the placenta and therefore provides a major line of defence against infection for the newborn. This can be reinforced by transfer ofcolostral IgG across the gut mucosa of the neonate. It diffuses readily into the extravascular spaces where it can act in the neutralization of bacterial toxins and can bind to microorganisms enhancing the process of phagocytosis (opsonization). This is due to the presence on the phagocytic cell surface of a receptor for Fc. 

Crude chloroform-methanol-water (30 60 8, v/v) extracts of immunostainedTLC bands were analyzed without further purification by nanoelectrospray low-energy mass spectrometry. The authors showed that this effective PLC/MS-joined procedure offers a wide range of applications for any carbohydrate-binding agents such as bacterial toxins, plant lectins, and others. Phenyl-boronic acid (PBA) immobilized on stationary support phases can be put to similar applications. This technology, named boronate affinity chromatography (BAC), consists of a chemical reaction of 1,2- and 1,3-diols with the bonded-phase PBA to form a stable... 

Some bacterial toxins have their effects on humans by interfering with the activity of the G-protein, that is G-proteins are involved in the action of some toxins, e.g. cholera toxin and pertussis toxin. Cholera toxin is a protein (mol. mass 87 kDa) consisting of A and B subunits, produced by the bacterium Vibrio cholerae. Subunit B binds to the plasma membrane of an intestinal ceU and then the A subimit enters the ceU. This subunit possesses ADP-ribosyltransferase activity, an activity which transfers the ADP-ribose from NAD to the a-subunit of G-protein,... 

Anthrax toxin is a bacterial toxin from Bacillus anthracis consisting of three parts protective antigen (PA), lethal factor (LF) and edema factor (EF). Both LF and EF compete for binding sites on the PA protein. The PA protein binds with high affinity to an as yet unknown receptor on macrophages and related cell types. When PA is internalized by the target cells, it functions as a shuttle protein for either EF or LF. Intracellularly, in the acidic environment of the endosome, EF and LF are capable of entering the cytosol by pH-dependent pore formation [139]. 

There is some evidence that bismuth subsalicylate can be effective in travelers diarrhea due to Escherichia coli and for nonspecific diarrhea by such mechanisms as binding bacterial toxins, bactericidal action and local anti-inflammatory effects. 

For the structural determination of the activated form of the a-subunit, use of A1F4 as a ligand was of great importance. AIF4 is an activator of GDP-bound a-sub-units and due to this characteristic — in addition to the bacterial toxins mentioned above — is often used for detection of G-proteins and for their structural characterization. In the presence of A1F4", permanent activation of the G-protein is observed G GDP is fixed by binding of AIF4 in a conformation that permits activation of the effector molecule. 

The minimum antibody binding domain, Fv, has also been linked to toxin to produce a more compact, recombinant immuno-toxin. The recombinant F -toxin appears to be more stable and exhibits less liver accumulation [27,28]. The immunogenicity of Fv-toxin as a consequence of the highly antigenic determinants of bacterial toxin remains a barrier to development. 

Kaolin is a naturally occurring hydrated magnesium aluminum silicate (attapulgite), and pectin is an indigestible carbohydrate derived from apples. Both appear to act as absorbents of bacterial toxins and fluid, thereby decreasing stool liquidity and number. They may be useful in acute diarrhea but are seldom used on a chronic basis. A common nonprescription preparation is Kaopectate. The usual dosage is 1.2-1.5 g after each loose bowel movement (maximum 9 g/d). Kaolin-pectin formulations are not absorbed and have no significant adverse effects except constipation. They should not be taken within 2 hours of other medications (which they may bind). 

The importance of these structures is clear by observing the numerous biomedical applications7711 that have been suggested for such compounds including inhibition of viral and bacterial infections, tumor eradication by stimulating the immune response, preventing toxin binding, and many others. Selected examples have been chosen to illustrate these potentialities. 

Monoclonal antibodies produced using this technology are now common tools in research because of their very high specificity. For example, they can be used to locate particular molecules within cells or particular amino acid sequences within proteins. If they are first bound to an insoluble matrix, they are also extremely useful for binding to and hence purifying the particular molecule from crude cell extracts or fractions (see Topic D5). They are also increasingly of use in medicine, both for diagnosis and as therapeutic tools, for example to inactivate bacterial toxins and to treat certain forms of cancer. 

Isoda, H., Kawasaki, Y., Tanimoto, M., Dosako, S., and Idota, T. 1990. Use of compounds containing or binding sialic acid to neutralize bacterial toxins. European Patent No. 385112. 

The primary duty of antibodies is to bind antigens. In some cases the penetration of cells by bacterial toxins or viral infections can be combat by generating such antigen-antibody complexes. Most of the time, an effector... 

After infection and immune cell activation, endothelial cells are variously activated to bind peripheral blood leucocytes. Bacterial toxins such as lipopolysaccharide (LPS), inflammatory cytokines such as tumour necrosis factors a and (5 (TNFa and TNFP) and interleukin-1 (5 (IL-ip) increase the synthesis of cell surface E- and P-selectins in endothelial cells. Histamine and thrombin increase PM P-selectins in endothelial cells and platelets. L-selectins are constitutively expressed in monocytes and lymphocytes. The selectins are involved in the initial adhesion of leucocytes with endothelial cells via selectin-selectin receptor interactions, for example, monocyte L-selectin-endothelial L-selectin ligand binding and T-lymphocyte-endothelial selectin-integrin interactions. This initial phase of leucocyte-endothelial adhesion enables an early stage of leucocyte rolling through successive formation and breakage of adhesive interactions. 

Some of the proteins are toxic in nature. Ricin present in castor bean is extremely toxic to higher animals in very small amounts. Enzyme irvhibitors such as trypsin inhibitor bind to digestive enzyme and prevent the availability of the protein. Lectin, a toxic protein present commonly in legumes, agglutinates red blood cells. A bacterial toxin causes cholera, which is a protein. Snake venom is protein in nature. 

Fishman PH (1982) Role of membrane gangliosides in the binding and action of bacterial toxins. In J. Membr. Biol. 69 85-97. 

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