The PDZ domain of EpsC is required for extracellular secretion of VesB by the Type II secretion system in <i>Vibrio cholerae</i>

The T2SS is common in Gram-negative pathogens, facilitating the secretion of various toxins and enzymes; however, the mechanisms of substrate selection and secretion remain poorly understood. Here, we demonstrate that the C-terminal PDZ domain of the T2SS "clamp" protein EpsC is only required for secretion of VesB in <i>V. cholerae</i> and that VesB's Ig-fold contains PDZ-dependent secretion information that can be functionally grafted onto a non-secreted periplasmic protein.