Genetic, biochemical, and molecular characterization of the polypeptide transport-associated domain of Escherichia coli BamA.

The BamA protein of Escherichia coli plays a central role in the assembly of β-barrel outer membrane proteins (OMPs). The C-terminal domain of BamA folds into an integral outer membrane β-barrel, and the N terminus forms a periplasmic polypeptide transport-associated (POTRA) domain for OMP reception and assembly. We show here that BamA misfolding, caused by the deletion of the R44 residue from the α2 helix of the POTRA 1 domain (ΔR44), can be overcome by the insertion of alanine 2 residues upstream or downstream from the ΔR44 site.