Interaction of RTX toxins with the host cell plasma membrane.

epeats in oins (RTX) protein family is a group of exoproteins secreted by Type 1 secretion system (T1SS) of several Gram-negative bacteria. The term RTX is derived from the characteristic nonapeptide sequence (GGxGxDxUx) present at the C-terminus of the protein. This RTX domain binds to calcium ions in the extracellular medium after being secreted out of the bacterial cells, and this facilitates folding of the entire protein.

Heterologously secreted MbxA from Moraxella bovis induces a membrane blebbing response of the human host cell.

Many proteins of the Repeats in Toxins (RTX) protein family are toxins of Gram-negative pathogens including hemolysin A (HlyA) of uropathogenic E. coli. RTX proteins are secreted via Type I secretion systems (T1SS) and adopt their native conformation in the Ca-rich extracellular environment.