In molecular biology, the cytotoxic necrotising factor family of proteins includes bacterial cytotoxic necrotising factor proteins and the related dermonecrotic toxin (DNT) from Bordetella species.

Cytotoxic necrotizing factor 1 (CNF1) is a toxin whose structure from Escherichia coli revealed a 4-layer alpha/beta/beta/alpha structure containing mixed beta-sheets.

[1] CNF1 is expressed in strains of E. coli causing uropathogenic and neonatal meningitis.

[2] CNF1 belongs to a unique group of large cytotoxins that cause constitutive activation of Rho guanosine triphosphatases (GTPases), which are key regulators of the actin cytoskeleton .

Bordetella dermonecrotic toxin (DNT) stimulates the assembly of actin stress fibres and focal adhesions by deamidating or polyaminating Gln63 of the small GTPase Rho.