The structural basis of autotransporter translocation by TamA

TamA is an Escherichia coli Omp85 protein involved in autotransporter biogenesis. It comprises a 16-stranded transmembrane. beta-barrel and three POTRA domains. The 2.3-angstrom crystal structure reveals that the TamA barrel is closed at the extracellular face by a conserved lid loop. The C-terminal beta-strand of the barrel forms an unusual inward kink, which weakens the lateral barrel wall and creates a gate for substrate access to the lipid bilayer.