colC

ColC is a protein toxin produced by certain strains of *Escherichia coli* (E. coli), particularly those belonging to the serogroup O157:H7. It belongs to the family of Shiga toxins (Stxs), which are also known as verotoxins due to their ability to cause hemorrhagic colitis and hemolytic uremic syndrome (HUS) in humans. ColC is structurally similar to Shiga toxin but differs in its mechanism of action and host specificity.

The ColC protein is encoded by the *colC* gene, which is often found on plasmids or bacteriophages within certain pathogenic E. coli strains. Unlike Shiga toxin, ColC primarily targets the intestinal epithelium, leading to inflammation and tissue damage. Its cytotoxic effects are mediated through the binding of its B-subunit to specific glycolipid receptors on host cells, facilitating the entry of its A-subunit into the cytoplasm. The A-subunit then inhibits protein synthesis, leading to cell death.

ColC is considered a virulence factor, contributing to the pathogenicity of certain E. coli strains. However, its role in disease is less well-defined compared to Shiga toxin, and not all pathogenic E. coli strains produce ColC. Research suggests that ColC may enhance the ability of some strains to colonize the intestinal tract and evade host immune responses, though its exact clinical significance remains an area of ongoing study.

The detection of ColC is often used in microbiological diagnostics to identify specific pathogenic E. coli strains. However, its presence alone is not sufficient to confirm disease causation, as other virulence factors and host factors also play critical roles in infection outcomes. Further research is needed to fully elucidate the role of ColC in bacterial pathogenesis and its potential as a therapeutic target.