Figure 7. AFM demonstrates that FeoB assembles as a homotrimer in solution.

Histidine-tagged FeoB was solubilized and purified from inside out vesicles in buffer containing 0.05% C₁₂E₈. (A) Low-magnification AFM images of a sample of purified FeoB showing monomers (➔), trimers (→) and hexamers (➤). Images are 500 nm square. (B) Gallery of zoomed images showing examples of a FeoB monomer, trimer and hexamer. Images are 59 nm square. (C) Volume distribution of FeoB. The peak molecular volumes are indicated. (D) Relationship between FeoB volume and oligomeric state.