The RTX toxin family is a group of exotoxin

Exotoxin

An exotoxin is a toxin excreted by a microorganism, like bacteria, fungi, algae, and protozoa. An exotoxin can cause damage to the host by destroying cells or disrupting normal cellular metabolism. They are highly potent and can cause major damage to the host...

s produced by gram-negative bacteria. All RTX toxins share a common gene organization and structural appearance. Gram-negative bacteria secrete the toxins into the extracellular space using the type I secretion system. RTX is an abbreviation of "repeats in toxin," which is a reference to the repeated peptide

Peptide

Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

 sequences found within the toxins. RTX toxins are divided into hemolysin

Hemolysin

Hemolysins are exotoxins produced by bacteria that cause lysis of red blood cells in vitro. Visualization of hemolysis of red blood cells in agar plates facilitates the categorization of some pathogenic bacteria such as Streptococcus and Staphylococcus...

s and leukotoxins.

Examples

The Pasteurellaceae

Pasteurellaceae

Pasteurellaceae comprise a large and diverse family of Gram-negative Proteobacteria with members ranging from important pathogens such as Haemophilus influenzae to commensals of the animal and human mucosa. Most members live as commensals on mucosal surfaces of birds and mammals, especially in the...

family of bacteria produce RTX toxins. The Vibrio

Vibrio

Vibrio is a genus of Gram-negative bacteria possessing a curved rod shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Typically found in saltwater, Vibrio are facultative anaerobes that test positive for oxidase and do not form...

genus, which include V. cholerae

Vibrio cholerae

Vibrio cholerae is a Gram-negative, comma-shaped bacterium. Some strains of V. cholerae cause the disease cholera. V. cholerae is facultatively anaerobic and has a flagella at one cell pole. V...

and V. vulnificus

Vibrio vulnificus

Vibrio vulnificus is a species of Gram-negative, motile, curved, rod-shaped bacteria of the Vibrio Genus. It was first reported by Hollis et al. in 1976. It was subsequently given the name Beneckea vulnifica by Reichelt et al. in 1976 , and finally Vibrio vulnificus by Farmer in 1979...

, also produce RTX toxins.