Autotransporter systems, a subset of Type V secretion, provide potentially the simplest mechanism for extracellular secretion of recombinant proteins. An autotransporter consists of an N-terminal Sec-dependent signal sequence, a passenger
domain and a C-terminal b-motif. The translocation is a twostep process. The target protein is transported into the periplasm
using Sec-dependent transport whereupon the b-motif forms a transmembrane pore through which the passenger
domain can reach the extracellular spac