Type II secretion system

The type 2 secretion system (often referred to as the type II secretion system or by the initials T2SS) is a type of protein secretion machinery found in various species of Gram-negative bacteria, including many human pathogens such as Pseudomonas aeruginosa and Vibrio cholerae.^[1] The type II secretion system is one of six protein secretory systems commonly found in Gram-negative bacteria, along with the type I, type III, and type IV secretion systems, as well as the chaperone/usher pathway, the autotransporter pathway/type V secretion system, and the type VI secretion system (some bacteria also utilize the type VII secretion system).^[2] Like these other systems, the type II secretion system enables the transport of cytoplasmic proteins across the lipid bilayers that make up the cell membranes of Gram-negative bacteria. Secretion of proteins and effector molecules out of the cell plays a critical role in signaling other cells and in the invasion and parasitism of host cells.