Directed evolution of a Cry1Aa toxin using phage display and biopanning was performed to generate an increased binding affinity to the Bombyx mori cadherin-like receptor (BtR175). Three mutant toxins (371 WGLA374 , 371 WPHH374 , 371 WRPQ374 25) with 16-, 16-, and 50-fold higher binding affinities, respectively, for BtR175 were selected from a phage library containing toxins with mutations in do...

Tritium-labeled toxin analogs were prepared by reduction with NaB(3)H(4) of either the toxin from Helminthosporium maydis race T or a toxin component from Phyllosticta maydis. These reduced analogs had high radiochemical specific activities, high biological activities, and plant specificities identical to the native toxins. A filtration assay was developed to test the binding of these labeled a...

1. Kinetic studies on the binding of 125I-streptolysin-O exhibited immediate fixation of activation toxin to natural and artificial membranes. Once fixed to the membrane no release of Streptolysin-O or Streptolysin-O-lipid-complexes has been observed. 2. In contrast to activated toxin (free SH-groups!), oxidized Streptolysin-O was shown to become also fixed to membranes, however, with different...

BACKGROUND Virus infected killer strains of the baker's yeast Saccharomyces cerevisiae secrete protein toxins such as K28, K1, K2 and Klus which are lethal to sensitive yeast strains of the same or related species. K28 is somewhat unique as it represents an α/β heterodimeric protein of the A/B toxin family which, after having bound to the surface of sensitive target cells, is taken up by recept...

Selective ligands are needed for distinguishing the functional roles of M2 receptors in tissues containing several muscarinic receptor subtypes. Because the venom of the green mamba Dendroaspis angusticeps contains the most specific antagonists known for M1 and M4 receptors (m1-toxin and m4-toxin), it was screened for toxins that inhibit the binding of [(3)H]N-methylscopolamine ([(3)H]NMS) to c...

Induction of cell cycle arrest in lymphocytes after exposure to the Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is dependent upon the integrity of lipid membrane microdomains. In this study we further demonstrate that the association of Cdt with lymphocyte plasma membranes is dependent upon binding to cholesterol. Depletion of cholesterol resulted in reduced toxin bi...

The immunodominant determinant of Pseudomonas toxin A was shown to cross-react with a normally inaccessible determinant in fragment A of diphtheria toxin. Trypsin-treated diphtheria toxin and fragment A of diphtheria toxin inhibited binding of toxin A antibody to whole toxin A, whereas whole diphtheria toxin did not inhibit this reaction. However, even at the lowest stringency no hybridization ...

Toxin-binding proteins of insect midgut epithelial cells are associated with insect resistance to Bacillus thuringiensis (Bt) Cry toxins. A 5378 nt cDNA encoding a 1717 amino acid putative midgut cadherin-like glycoprotein and candidate Cry1Ab toxin-binding protein was characterized from Ostrinia nubilalis. Intraspecific alignment of partial O. nubilalis cadherin gene sequences identified varia...

Soluble receptor decoy inhibitors, including receptor-immunogloubulin (Ig) fusion proteins, have shown promise as candidate anthrax toxin therapeutics. These agents act by binding to the receptor-interaction site on the protective antigen (PA) toxin subunit, thereby blocking toxin binding to cell surface receptors. Here we have made the surprising observation that co-administration of receptor ...

Abstract Insect pests are a major cause of crop losses worldwide, with an estimated economic cost $470 billion annually. Biotechnological tools have been introduced to control such insects without the need for chemical pesticides; instance, development transgenic plants harbouring genes encoding insecticidal proteins. The Vip3 (vegetative protein 3) family proteins from Bacillus thuringiensis c...