Fig. 7

Assembly of the YaxAB pore and comparison with ClyA. a Schematic overview of our proposed YaxAB pore assembly pathway at targeted membranes. i) YaxA binds to membranes via its hydrophobic foot, ii) after which YaxB, harboring no membrane binding capacity on its own, is recruited. iii) At this stage, YaxB’s foot domain rearranges to its membrane-inserted state, stabilized by YaxA’s hydrophobic foot. iv) Another membrane-bound YaxAB dimer interacts with the first dimer via the trans YaxA–YaxB contact sites. v) Further association of protomers eventually drive formation of the YaxAB pore. The possibility of off-pathway oligomerization, by subunit interaction prior to membrane binding, is indicated by the gray arrow. Red outlines indicate the exposure of membrane-active moieties. b Comparison of YaxAB (PDB accession code 6EL1) and ClyA (PDB accession code 2WCD¹²) pore architectures. For a to-scale comparison with the ClyA complex, the structures were tiled in UCSF Chimera. The golden bar indicates approximate membrane boundaries