Corynebacterium diphtheriae toxin is a toxic substance produced by the bacterium Corynebacterium diphtheriae, which is responsible for causing the infectious disease known as diphtheria. This gram-positive bacterium primarily infects the respiratory system and is characterized by the production of a potent exotoxin known as the diphtheria toxin.
The diphtheria toxin is classified as an AB-type toxin, consisting of two distinct subunits: subunit A and subunit B. Subunit B is responsible for binding to specific receptors on the host cells, enabling the bacterium to attach and gain entry into the cells. Once inside, subunit A is activated and exerts a toxic effect.
The toxin functions by inhibiting protein synthesis within the infected cells. Subunit A catalyzes the transfer of ADP-ribose from NAD+ to the eukaryotic elongation factor 2 (EF-2), leading to the inactivation of EF-2. EF-2 plays a critical role in the process of protein synthesis, and its inactivation disrupts this essential cellular function.
The inhibition of protein synthesis by the toxin impairs the ability of the host cell to produce new proteins, leading to cell death. This process contributes to the characteristic pseudomembrane formation seen in diphtheria infections, where dead cells and immune cells accumulate in the infected area.
Corynebacterium diphtheriae toxin is a major virulence factor of the bacterium and plays a crucial role in the pathology of diphtheria. To combat the toxin, effective treatment typically includes the use of antitoxins, antibiotics to eliminate the bacteria, and vaccination to prevent future infections.
