Where is the diphtheria toxin gene located?
Diphtheria toxin (DT) is an extracellular protein of Corynebacterium diphtheriae that inhibits protein synthesis and kills susceptible cells. The gene that encodes DT (tox) is present in some corynephages, and DT is only produced by C. diphtheriae isolates that harbor tox+ phages.
What does diphtheria toxin bind?
The toxin binds to heparin-binding epidermal growth factor precursor (HB-EGF). The complex undergoes endocytosis by the host cell. Acidification inside the endosome induces translocation of the A subunit into the cytosol.
What is the target organ of diphtheria?
Diphtheriae toxin does not have a specific target organ, but myocardium and peripheral nerves are most affected [12].
What cells do diphtheria infect?
Once infected, the bacteria quickly multiply within the body and spread through the inner lining of the throat, mouth and nose. The bacteria produce a toxin that kills cells in the throat. These cells then join to form the grey–white membrane that is typically seen in cases of diphtheria.
Is diphtheria toxin an AB toxin?
The Diphtheria toxin also is an AB toxin. It inhibits protein synthesis in the host cell through phosphorylation of the eukaryotic elongation factor 2, which is an essential component for protein synthesis.
What does the diphtheria toxin do?
Diphtheria toxin (DT) is an extracellular protein of Corynebacterium diphtheriae that inhibits protein synthesis and kills susceptible cells.
What causes diphtheria toxin?
Diphtheria bacteria usually spread from person to person through respiratory droplets, like from coughing or sneezing. Diphtheria is a serious infection caused by strains of bacteria called Corynebacterium diphtheriae that make a toxin (poison). It is the toxin that can cause people to get very sick.
What type of toxin is diphtheria toxin?
Diphtheria toxin belongs to the so-called bifunctional A–B toxins (Figure 2-10). Portion A mediates the enzymatic activity responsible for halting protein synthesis in the target cell while portion B binds to a cell receptor and mediates the translocation of the A chain into the cytosol.
How is diphtheria toxin regulated?
The tox gene has been shown to be regulated by the heavy metal ion-activated regulatory element DtxR. In the presence of divalent heavy metal ions, DtxR becomes activated and binds to a 9 bp interrupted palindromic sequence.
What effect does diphtheria toxin have on host cells?
Diphtheria toxin kills human cells because it delivers its enzyme domain DTA into their cytosol where it inhibits protein synthesis. After receptor-mediated uptake of the toxin, DTA translocates from acidic endosomes into the cytosol, which might be assisted by host cell factors.