Diphtheria toxin belongs to a group of toxic proteins that enter the cytosol of animal cells. We have here investigated the effect of NH2-terminal extensions of diphtheria toxin on its ability to become translocated to the cytosol. DNA fragments encoding peptides of 12-30 amino acids were fused by recombinant DNA technology to the 5'-end of the gene for a mutant toxin. The resulting DNA constru...

A 10-aa motif in transmembrane helix 1 of diphtheria toxin that is conserved in anthrax edema factor, anthrax lethal factor, and botulinum neurotoxin serotypes A, C, and D was identified by blast, clustal w, and meme computational analysis. Using the diphtheria toxin-related fusion protein toxin DAB(389)IL-2, we demonstrate that introduction of the L221E mutation into a highly conserved residue...

There is a global shortage of equine-derived diphtheria anti-toxin (DAT) for diphtheria treatment. There are few existing data on serum antibody concentrations and neutralizing activity post-treatment to support development of new therapeutics. Antibody concentrations were quantified by ELISA and anti-toxin neutralizing activity by cytotoxicity assay in serum from 4 patients receiving DAT for s...

In diseases such as diphtheria and tetanus, almost all the clinical symptoms terminating in deat.h are due to specific soluble toxins produced in civo (or in vitro) by the diphtheria and t&anus bacilli respectively. Although diphtheria toxin has been isolated as an essentially pure protein which has been reasonably well characterized both chemically and physically (l-3), almost’ nothing is know...

In diseases such as diphtheria and tetanus, almost all the clinical symptoms terminating in deat.h are due to specific soluble toxins produced in civo (or in vitro) by the diphtheria and t&anus bacilli respectively. Although diphtheria toxin has been isolated as an essentially pure protein which has been reasonably well characterized both chemically and physically (l-3), almost’ nothing is know...

Ion fluxes associated with translocation of diphtheria toxin across the surface membrane of Vero cells were studied. When cells with surface-bound toxin were exposed to low pH to induce toxin entry, the cells became permeable to Na+, K+, H+, choline+, and glucosamine+. There was no increased permeability to Cl-, SO4(-2), glucose, or sucrose, whereas the uptake of 45Ca2+ was slightly increased. ...